[chiphead]

I am not aware of a high volume oil pump for Pontiac other than a Luhn or something. There is a melling 60PSI pump and a 80PSI pump, same volume. If the oil pressure is going 100 PSI with 30wt, I'd expect it has the 80 PSI pump. Does it go over 65 PSI at high RPM when oil is hot?

Do you know the clearances and parts used? Does is list a PN for the oil pump?

I can't see a reason to run a single-weight oil in a street motor that doesn't have exotic internals. Maybe the builder is old school and is worried about a multi weight oil breaking down at high temps? Modern oils stand up to heat a lot better, it's not 1985.