Heres a little tip to save you afew problems later on, check that those head gaskets have the 2 small steam holes in them being a chevy 400 block it will have siamesed bores, those 2 extra holes are for helping water circulation in these 400 blocks.

heres another one while the heads are off see how much of a ridge is below the top of the bore if it's large the engine could be coming up to rebuild tme, I'm only saying this because I noticed you mentioned the the bores were nice and shiney in your first post.