Hello, I'm new to this forum and I have a 400 Small Block. I would just like to ask if all chevy heads would fit from the 350 small block various years. Just fit in general not depending on the size of chambers and valve size I choose... or is there a specific casting number only that would fit? Thanks.  

Gen I small block Chevys were wonderful, just about everything will work from '87 and earlier. For a few years after '87 you will need a different intake manifold is all though, just stick with the Gen 1 stuff and you can make it work.

Just remember to have steam holes drilled in whatever heads you decide to put on your 400.