Thanks guys, that helps. Quantum Mechanics was the one I was looking for. My transmission is not long for this world and I need to find a solution. I'm sure gears are worn in it, and syncros certainly are.
I'd love to fit a 5 speed conversion, but the prices are really steep. I've looked at the Ford T9 conversions and Frontline now has them with a shortened remote that apparently doesn't require carving sheet metal. Closing in on nearly $3K for the kit plus shipping is really a stretch.
Wish I had grabbed some of those Datsun gearboxes back in the days when they were just a couple hundred dollars. Hindsight is always great.