I would consider 120gr T7 loose in a Rem700 a MAX Load.
Good way to tell if you are pushing things too hard for the barrel is your accuracy will go out the window with higher charges as a result of blow-by. Also, the higher charge can cause the sabot or projectile to "skip" over the rifling.

I'd suggest starting with 80-90gr and work up to 120gr and see where things shoot the best.
In my Rem700, I found a very accurate and effective deer load with 105gr T7 under a 300gr Hornady XTP. Killed many deer with this setup.

Let us know your results!