Thanks for all of the contributions. I will re-double by HSS grinding efforts/geometry, and see where that takes me! I acknowledge the opinion, expressed by many, that the standard ML7 speed range is more than good enough.
On my first Myford I fitted a 2,800 rpm motor with no problems. Kept it for a couple of years before upgrading. The myford C7 capstan had bronze bearings and a faster motor.