400 into 65 valiant

I don’t see much info about big blocks in older a-bodys. I’m going to attempt it. Anyone else? What do I need to look out for?
/6 about to come out. Have the trans Dapt motor mounts for 67 and up anticipating some fab work, going to see if the stock truck manifolds might work. Otherwise I think the Schumacher tri-y headers should work? Everything the sell is for 67 and up. Thanks