Make absolute sure that they check allllllllll clearances. Also, dont JB weld **** inside the engine, especially if you are going this far into the build. I'd assume you are getting roller rockers, so make sure that the pushrods are to the correct length.
Also, for the "wth is on the heads"....if you're talking about the 1st and 2nd head photos, that should be Valve-lapping compound.