Clearance while rotating the reamers is a problem.
The chucking reamer was ground flat, and a steel rod was slotted with a hacksaw to receive it. Reaming the .1875 diameter holes is a low-torque affair, so this 'reverse screwdriver' worked OK. For the larger stabilizer bushings, I think I'll grind the .4375 reamer to allow driving with a 1/4" square socket.