Kidneys from anything need a lot of work to taste halfways civil. I will suggest the same, feed it to something else and eat the something else.
Heart is going to taste very dark, be prepared for that. Liver and heart will have that taste as they are blood-tissue. (that is why in chicken and turkey you have the legs be dark meat, they are the working part of those types of birds and are generally more blood/iron rich). Heart goes good slow cooked and put a strong spicing with it, tongue and heart usually are good for black pepper as well as onions. For this kind of cooking I crack mine fresh with a grinder.
I hope you saved the intestines and cleaned them for making your sausage...
Peeling and roasting the tail is time honored snacking. Are you going to pickle the feet and ankles? Boil off the head and get the cheek meat?
I like to put the heart in a brine for a day or so before I cut it very thinly to use in stir fries. Onions, garlic, oregano or sage and then whatever veggies you have on hand. I find that it goes quite nicely with anything that would normally call for tough beef cuts.
I like the liver in small amounts cooked in butter and lots of garlic and onions. I cook it so that it's just barely cooked through. If you go too long it gets grainy and kinda funky. Remove the liver and veggies from the pan and then use some red wine (dry) to scrape up the pan drippings and reduce that into a sauce for the liver. It's pretty good. Like I said... small amounts. A little pastured pork liver can go a long way.
You could also make terrines or patte with liver. Served cold it can be a nice treat before a meal or served on a toasted piece of bread as part of a salad.
I've tried kidneys and while I'm sure there's a way to make then=m work well, I haven't found one preparation that I like. I do have a guardian dog that happily will eat them though. Funny thing is that he only eats them once he's buried them for a few days first. never fresh. Either way, he's happy and I get to make good use of the rest of the pig.
I didn't have pigs liver but usually I make liver as Albanian liver it is really yum. Google for a recipe, basically you cut it into nice strips then coat it with a bit of flour and the following spices, black pepper, garlic, sumac thyme and chilli (maybe I forgot something) on a bed of red onions and pasrley on the top.