I also installed the Moss 5-speed transmission for the exact same reasons. I really got tired of the "Grunch!" every time you selected first or reverse, no matter how careful you were! More "character" than I wanted. Throw in the Pertronix ignitor kit, and that package of new technology in the old relic really makes a enjoyable, fun-driving roadster out of it - just what the boys at Abingdon intended. 
Still can't pass anyone going uphill, however ...