Hi Matthew, I hope it's OK for me to be forthright with my view; please don't take it as a condemnation, just a different point of view.
If I had your property and wanted sheep on it, I wouldn't have done anything that you did. I can understand why you did it, as it's probably what the conventional ag people advise, but there are other ways to approach it.
First, I don't know what you cleared from your pasture, but I'm going to assume that it didn't consist of plants that are poisonous to sheep. If it was, you get a free punch the next time you see me, but not in the face, I'm not pretty
enough to take damage there. Otherwise, what you had there to begin with would've been food for the sheep; maybe not top quality, but still edible. Tilling the soil is very disruptive to the organisms that live in the soil and even conventional ag is moving towards 'No till' methods, though they use herbicides to do that. Soil also usually has a huge amount of seed already that's just waiting for the right conditions to grow. Unfortunately, I've seen a lot of clear-cut logging, but I've always seen the
land sprout vegetation afterwards from the seeds already there. It may not be what you want, but it's often what the land needs, at least initially. So, I would've fenced the pasture, set it up for rotations every 1-3 days, let the sheep eat it all down to the ground (they're very good at that), then see what comes up. If you've got the right stocking rate, by the time they circle back around, you'll have slightly better pasture for them to eat. Rinse and repeat, and you'll eventually get a much higher quality pasture through pressure on the undesirable species and the fertility the sheep add through rotational grazing. You can seed behind the sheep, though I think the best thing to do would be to broadcast seed BEFORE the sheep graze, let them clear out the growth at the same time they push the new seed into the earth and fertilize it with manure and
urine.
You didn't do that, but it's not the end of the world, not even close. I figure you've got two options: let it grow what's already in the soil or seed it yourself. If you choose to seed it now, you may find that the conditions aren't great for your seed mix so the seed you sow will be out-competed by the
native seedbank. By using a mix you're increasing your chances that one or two species in the mix grow well, but don't expect only your seeds to germinate.
For seeding rates, I think a lot of your varieties would be in the 5-10 lb/ac range. If you want to seed it all, I'd seed at half the rate suggested, or at the lower end of a range, but I like to experiment, so I'd do it in strips and I'd leave at least a paddock bare, just to see what comes up. Unless the original pasture was toxic, I'd leave 1/4 of the pasture unseeded, the next 1/4 seed at full rate recommended for reseeding, next 1/4 at 25% of recommended reseeding rate, then half the rate for the last 1/4. This will give you an idea of what works and how much seed you need. With rotational grazing you'll improve your pasture and you can always seed in front of the sheep to thicken your stand.
Hope that helps.