I also wonder how you are going to fixture the action.mounts and rings and align them correctly with the machine you are going to use to power the reamer. Hand reaming them will not change alignment.
One setup I saw (but never used myself) to ream one out-of-alignment ring to a straight one used a standard 1" machine reamer with a square ground on the end for a tap handle. A long bushing with a 1" OD and an ID to fit the reamer shank was made.
The bushing was secured in the straight ring (with the reamer in it). This lined the reamer up so one could carefully hand ream the bad ring.
I don't imagine the above would work very well if the bad ring were
way off though, and it would no doubt work better on aluminum than steel rings.
The only time I had to line up one ring on 1/2 of a two-piece mis-mounted base, it was straight enough to lap in with a 1" bar by using grease on the straight ring and valve grinding compound on the bad one until I got ~80% contact where the ring clamped the scope tube.