[vector1]

don't know what the nascar guys do but i run a blowoff valve on one of the valve covers, keeps the gaskets in good shape if you lose ring control or build crankcase pressure for some reason.

i run a vented crankcase, but am going to use a peterson vacuum regulator to limit vacuum to 12". vacuum does make power.

don't make any vacuum if you are breaking the engine in, the rings will not seat correctly from what i have read.

why are your leakdown numbers so bad? with a lot of leakdown you might have problems pulling a vacuum.