Just keep an eye open for refinish marks under the grips, obvious refinishing signs on the exterior of the gun like over polishing of stampings, and rounded edges that should otherwise be sharp, etc.
Any -2 or -3 gun will be fine with factory full power loads or equivalent handloads, though -5 and later guns have all the endurance package upgrades and will handle a steady, day in and day out diet of the full power stuff much better.