Question on soil pH

I have very acidic soil, as low as 4.5.  This year I'm planning on putting in 6 4x8 raised beds.  The soil I bought to fill them has a neutral pH.  Most of what I'm planing likes soil in the slightly acidic range.  I'm working on increasing the pH in most of my beds, so it feels odd to think of what I need to add to soil to bring the pH down.  Can I swap some of the soil I purchased with some of the soil in my acidic beds to lower the pH in the new raised beds to something like 6.5-6.8?  I'm not expecting this to do much in the acidic beds, I'm just hoping to use what I have to lower the pH somewhat in the new beds.

that soil sounds perfect ph for blueberries, plant them once and they get bigger every year, no mus no fuss and if you pick them before the birds you will have a multigenerational crop

I do have blueberries growing on the property.  Blackberries too.  I took soil samples and am waiting for the results.  I may increase the pH if it's in the low end of what the plants can handle.  I also want to plant many more types of berries, and not all of them can handle the very high acidity.

We bought the property to homestead on, never dreaming the pH would be so low.  So I need to raise the pH where I have or plan to have vegetable beds.  

I see you have asked previously about raising the PH.

Have you decided on the best way to do this?

I feel adding amendments would be better than using soil from the other beds.

I haven't been able to do anything about it until now, and it's late for trying to amend the pH.  I'm looking at Turf-pro Mag-I-Cal by Jonathan Green.  It's supposed to work over weeks, not months.  I plan on putting acid loving plants in my most acidic beds - potatoes, peanuts and stinging nettle.  So if I can nudge the pH a bit higher now, that would be good.  If not, it's still no a disaster.  I can do more with it in the fall.

My question now is about the raised beds. I bought soil that is pH neutral, and most veggies like a pH that is somewhat lower than 7.0.  I'm spending a lot of money this year, and I just can't see buying something that will lower the pH in these beds when I already have plenty of acidic soil.  I don't think it would take too much 4.9 pH soil to bring 7.0 pH soil down to something like 6.5 to 6.8 pH.  If mixing soils will work, the question will be how much acidic soil of a given pH to mix with the neutral soil, and how long before I can test to get the results of the mix.

This is a math problem.
Lets say you have a cubic yard of 4.9 ph soil and a cubic yard of 7.0 ph soil. Mixing them together should create something around 6.0 ph. 4.9 +7.0 divided by 2= 5.95.
If you want the ph a little lower, adjust the amount of 4.9 ph soil upwards and do the math again.
So 1.5 yards of 4.9 ph + 1 yard of 7 ph goes like this:
(1.5x4.9) + 7.0 divided by 2.5 = 5.74 ph

If you want to get to 6.5, you have to do the math backwards. Starting with the end result you want, 6.5, how much 4.9 do you add to a cubic yard of 7.0?
4.9x +7.0/ x+1 = 6.8 Without doing all the algebra, I can tell you that about 1/8 of a yard of 4.9 ph soil added to a cubic yard of 7.0 ph soil will get you 6.76 ph.
So in layman's terms for every 8 shovels of 7.0 soil add a shovel of that 4.9.

It may take a while (months even) for the ph level to truly average out if you are mixing by hand.
If you have a rolling barrel cement mixer, you can get a much better mix of the soils by putting them in the mixer and letting it spin for a bit.

Thank you.  Doing the math isn't difficult, it's just a matter of averages.  I was hoping it would work that way, but I wasn't sure.  But if it takes several months for the pH to fully level out, what impact does that have on the plants?  If I make the pH say 6.8, how well would a plant that likes that pH do in the freshly combined soil?

Mind you I'm no earth scientist, but I frequently work with acids and other caustic substances that I have to hand mix to get the proper strength I also know a bit about dissolving solids in solution. So it occurs to me that the secret to rapid equalization is the addition of liquid, most preferably water.

The ratio of acidic soil to neutral soil in the equation is also pretty low. A good mixture will negate any seriously adverse effects of the more acidic soil because it is present in areas of low concentration.
My limited understanding of plant ph preference is that the most common vegetables prefer a sweeter soil, but that doesn't mean they will fail to produce in a more acidic soil or a more basic one. It just means the yields will be smaller than they would be in the optimal ph level. I really doubt that planting directly in that neutral soil will have much effect on the yields.

Most of my gardening has been done in store bought soils that I have amended over years to get a good quality. Making good soil takes time.

Most vegetables like slightly acidic soil.  Beans, corn, squash and carrots like 6.0-6.8, There are several that can also grow in neutral to slightly alkaline.  

Thank you for pointing out that many of the vegetable also like neutral to slightly alkaline soil.  I was too focused on how much acidity the plants could handle.  I was looking at ht low end of their preferred range.  I can leave a couple of the beds alone,  But I still should get the pH down to 6.8 in a couple of the beds if I can.  A pH of 6.6 would be better.  How doable would that be?

My experience is that plants are not really that fussy when the pH is at least n the ballpark. It's only when the pH is way out of the range that they prefer that I've seen negative effects that need to be remedied. Personally, I'd try growing what you want to grow and see how it does. If you see things like clorosis or other signs of nutrient deficiencies, you could consider altering the pH of the soil. Be careful, however, as something like blossom end rot could be due to a high soil pH or it could be something as simple as not watering enough.