The crossover is also to feed the hydraulic lifters. So it will still function for that as well as helping #4. As stated in the past you do not need to drill the front oil passage. It only feeds the #1 main and 1 rod bearing.
I got overzealous wanting maximum 5/16 flow to all main bearings.
Better to have let that one slide than this.
Anyway. the expansion plug should keep water out of the galley and vise versa.
I could tap the end of the galley for added strength and plug it just as I did the main feed coming up but don’t think that’s necessary.
The outer plug will keep water out from behind the cam cover.
