If your 228 is only building 30 psi of oil pressure, then either its a Chevy engine (go ahead Chevy guys...make my day) or it's not working properly.
GMC engines were 60# of oil pressure as stated above.
Yes, a "B 228" would have the cylinder bore punched out 0.005" over but the rod and crank journals would be standard as indicated in the shop or maintenance manual.
