K.. since we are discussing and not arguing for once bout 318s... my 318 is a bone stock '85 bottom end... keep under 6k and treat it nice? just curious where the worry point should start...
IMO, worry point is how hard it’s used and how often.
If it’s a RPM worry, I’d say anything past 6500 unless you know how big the oil passages are & couple that with oil PSI.
10 PSI per thousand RPM is very good to have and shouldn’t be a problem.
If the oiling passages are smaller than the books recommended size, this could be an issue above 6500. Spinning past 7K, I’d recommend going above and beyond the recommended modifications and address every passage in the block making it slightly larger, rounding corners instead of the 90* turns, bushing lifter bores, etc.