I have no clue. Ill look around, but I already did most of the work. All I need to do is bolt the heads to the manifold and see where the mark is, then cut the gasket with an exacto knife, and I should be good. Plans are to stick the blockoff to the manifold with some high temp formagasket. The locktite stuff is rated up to 650*F and the permatex to 500*F. If my creaky brain remembers right.
Gotta pick up a 3/8 - 16 tap to clean out the threads first. Maybe they'll have one at home depot on my way home from work tomorrow.