Thanks for the insight on the motors, I was hoping to be able to do something to boost the power for bigger jobs. Do you think they'd work in place of reduction pulleys on a jack shaft? I know metal is turned at much slower speeds, and that's one of the ways I'd thought to do it.

The C-channel size was already determined (and free btw), it's 3 x 1 3/8 x 3/16, and I plan on a 48" length (before tailstock, and planned to leave a gap between the ways and headstock body) Thanks, that does provide some food for thought, but I've never turned metal, so many aspects of the differences are new and mysterious to me. My question regarding the width of the ways really tends to what sizes would work with an existing carriage plate, and that I've no idea about.