Welp, I can tell you I never use them. The engine in my car doesn't have them. The R block deal I'm doing next won't have them. Any chance your plate was junk? I've done it with the OE plate, a gear drive and the magnum tensioner plate and never had a low oil pressure issue.
How low was the pressure? You leave a 3/8 plug out and you still have some pressure. How much could possibly leak by the plate?
