Is 20W-50 too heavy for my 340?

I just changed my 360 out from 10-30 to 20-50, oil pressure with the 10-30 would bottom out in gear when warm, now I hold steady at 10-50 pounds idle to under load. For reference its a mostly stock 1973 360 that as far as I know hasn't been rebuilt, so my guess is the bearings are pretty loose. It just depends on how worn the engine is, but if it's mostly stock I'd say your fine, especially with the Temps your working with