Thanks John S, I've taken on board your sizing advice, and probably made a huge mistake by ordering 3x DM556s, I'm a sucker for a gizmo :)

I've also got a 33V toroidal on the way for a 46V supply.

On the subject of drive ratios on the X and Y axes, I have a '92 machine and that has 12/20 pulleys to give 1.5mm per rev or 0.0075mm per whole step. I noticed in mikegolding's thread "Boxford VMC190 Retrofit Problems, axis sounds very rough" that his '98(?) machine had 16/20 pulleys to give 2mm per rev or 0.01mm per whole step. He gets the more pleasing 100 steps per mm compared to my 133.3333333333333333333333333333333333333333333333 333333333333333. My OCD is kicking in... At this point I don't intend to do anything with steppers or gearing, but clearly the options are there.