Originally Posted by
Steve_sr
..
I will probably invest in a straight flute adjustable hand reamer as it will self-center better with its slight barrel shape. Is this thinking
Yes, an adjustable reamer is your best option. However they can also be had with a slight helix, about 5 degrees or so.
While not absolutely necessary, the helix helps bridge the slot, so try for one those.
Also, the good news is that there should be no reason to ream the frame itself. The builder would have done that in order to fit the original sleeve.