Strange you should have encountered difficulty with a Reeves Drive that students the world 'round have been abusing to no avail for years. Speed on low end was ~375 if memory serves, which was certainly slow enough for any reasonably rounded 12" piece, but a bit of a pucker when turning 20" outboard.
Never found the gap to be a problem. With long jaws I could get the rest or steady in behind without dismounting the piece or the chuck, though I would not recommend working around the headstock regularly. Silly to put yourself in that position when you have a good set of jaws to reverse the piece. Think the only time I used it for its avowed purpose was when making tops for candlestands.