How do the rods and main bearings looking?
If they are good don't fix what ain't broken twocents work
Lots of misinformation out there about oiling issues on B and RB block in the main oil galley feeds to the main bearings, full groove main bearings, good supply of oil and the proper(001+ for each inch of journal diameter), NOT TIGHT bearing clearances have worked for me for years and years up
Thin oil, high volume oil pumps with 80 lbs. bypass springs in the high volume pumps and adequate bearing clearances are the key to making these motors live up to 7500 RPM up twocents

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)