Well, if you are looking for non-Chinese distributors, better stick with the stockers. It looks like MSD is heavily Chinese these days at 2-3 times the price. I'd guess Pertronix is too?? Adapting SBC distributors gives you more options, but many of them are Asian as well unless you have an inventory of older US-made stuff.
Tires I don't know, it seems like it's a crap shoot at best. The last set I bought was Michelin. I would have thought the Goodyears were top-tier but so many of the American brand names are manufacturing elsewhere. You almost have to look it up every time you are ready to buy a set. I guess there is a code on the tires, or very fine print in some cases. That's a tough market, and trailer tires take a lot of abuse.