The timing cover you are using is from and Atlas/N15/P11 rather than a '68-'69 Commando (25186 AB). See DynoDave's page http://atlanticgreen.com/NHTtimcvr.htm This is not a problem as the Atlas cover dumps any overpressure oil into the timing chest where the Commando channels this oil back into the engine cases. Note there is no hole in the cover adjacent to the oil pump, but the case and the gasket does. The cover will block this hole and overpresssure oil will be dumped into the timing chest as in the Atlas. However, using a Commando cover on an Atlas would not allow the oil from the OPRV to be vented in an overpressure condition. I mention this so you don't panic when you realize the oil passage in the block is covered.