The reusable reinforced silicone gaskets are very good. I've probably tried at least a 1/2 dozen v. cover gaskets over the years, and they're the best I've found. But if you're trying to seal with "aluminum foil" v. covers, that may be problematic.
I've taken some old SB mopar v. covers and cut the top off them so I can watch the valvetrain oiling and the pushrods spinning. It's a little messy, still, but as long as you don't rev the engine up, it's not horrible. If you think it could be a problem, I wouldn't wait to figure it out for sure.
