The 400HO carb and intake manifold for automatic is the same as the 400, so it will be much easier to find. A reproduction cam is readily available. The 400HO had a different valve train. I haven't looked into how hard it would be to find matching parts, but as Vikki said, its not necessary- a 400 valvetrain will fit just as well. The longbranches are not there so that will be an exhausting search, but you can always use the RARE reproduction manifolds unless/until you find originals. I agree regarding the crate- better to put a cheap 350 or similar Pontiac in there temporarily. For research on the 400HO automatic, check out JimC's site: JimC2002 400HO automatic
