Paul, back in the day we would rebuild old Harley transmissions using hand-picked rollers (needles) from a collection of various sizes, sized based on the shaft OD and race ID. I've seen roller availability in a vast array of sizes, and thought about machining a smaller OD race, matched to smaller diameter needles, fitted to that 14mm shiftshaft, with maybe 0.002" running clearance. The outer race shell could be cut in a "U" cross-section (to retain the needles). Full-compliment, packed with grease, only +/- 20° rotation, side loading well below supplier specs. Just a thought...