I think what he means by "tall fill" is to fill the block with block hardener or "rock it" as some people say, I think he's saying fill it to the highest water jacket. I first heard the term when my dad bought an old Sox & Martin HEMI block for $100 (it turned out cracked, cool coffee table) it was filled to the lower water jackets or "half rocked" hope this helps, some of the car lingo is confusing lol
