Yup, I ran 20/50 Valvoline in my Swinger. Had 410 stroker in it and I used the EMD Solid lifers from Johnson. I also had Oil thru manton push rods to keep pressurized oil on the ball and cup. My oil pressure was low like yours until I wicked it up. I had like 10-12 PSI at Idle and around 45-50 PSI driving around. Get on it and it would go 65PSI. Cold it would hit 60 PSI at Idle and after it warmed up it would go to 10-12 Psi again at Idle.
