For shooting commercial i think id go with 54r. the 308 commerical loads are often catered to bolts that might be bad even if winchester loads are well under max specs. i think most of the spec loads are going to be at least 4ksaami psi under max for liabilities. who knows how long 300wsm holds up or if it will fail in that config. magnum stuff is scary i would only shoot 300wsm with string hiding behind somtin..
i figure standard akm bolt 762x39: 3.14 * .2235^2=.156" bthrust 8000psi@51500max, modified in 54r pressures 3.14 * .2435^2=.186" bthrust 9670psi@52000psi 10500psi@56500max and with 308win 3.14* .2354^2=.174" bthrust 10800 @62000max . medium loads i hope might get around 17% more bthrust with 54r and similar pressure 308. The heavier 203gr 54r spam loads are probably closer to max psi and greater weight bullets add more stress on bolt lugs plus it overgasses because of the load difference thats why peoples PSLs have excessive wearing after firing many heavy grainers and no regulated gas.
the 54r case is more limited in pressures, 56.5k psi and 7.62x39 is 51.5k psi so 54r is at least around 6k less than max 308win.. My purpose would be long range target/hunting maybe elk out of standard akm parts.
now i dunno which idea i like more, for ak700 remington rifle you describe id go with big and slow round 250gr 358 win or heavier 300-400gr 45/70 like calibers. those could be made upto mimic rus 9x39 for a subsonic thumping ak and the weight of the round would make it effective on med/big game