That's a good point, Paul. I like the copper spray because it does release easily. Sometimes, though, you wind up working with a case or cylinder base surface that's not really bad enough to justify stripping the cases and running to the machine shop but not good enough to inspire confidence either. When I run across that I have no reservations about using a very tough sealant like Permatex Ultra Black. Re. separation, right, you don't want to beat on the fins. Bolt a piece of steel bar stock long enough to extend past the edges of the cylinder across the 8 mm. threaded holes in the cylinder. Tap on that until you get a little bit of separation at the base, then insert wood carpenter's shims if needed.
ebb0tk, member hooser (Gary Hoos, of Hoos Racing) recommends assembly with no base gasket if higher compression is desired. If he doesn't chime in here you might send him a message and ask what sealant he uses. If you're using stock pistons you should have plenty of room in squish and valve clearances, but some big bore pistons will show you no mercy on squish clearance. Be aware that cam timing will be slightly retarded by lowering the deck, making things a bit livelier at higher rpm. Been there, done that, liked the result, but you may not. 2M posted his research on effect of deck height on valve timing awhile ago. If a search doesn't turn it up for you I'm sure he'll guide you to the post.
