Certainly lots of race engine without valve seals out there. Not sure I would go that way with a nitrous deal. Oil will promote detonation, never a good thing but worse on the bottle for sure.
As for the vacuum pump I would use something better. Hard to beat a Moroso 3 vane an no regulator IMO for most. Moroso 4 vane is better and Star would be the top if you are looking for maximum vacuum.
"I am not ashamed to confess I am ignorant of what I do not know."
