Engine braking is a wonderful thing as you discovered! Not as much need for disc brakes if your overall ratio is low enough. On my two 5 speed bikes I'd say 80% of my braking is handled with engine compression coupled with down shift. Though the Simplex has dual disc the Harley Peashooter is a coaster rear and Sturmy drum up front. The Harley stops just fine, but pure clutch and stops take a while.
Mags, in post 261 this thread you said the final ratio was 12.25 to 1. Did the performance suit you with that ratio other than the slippage? If so duplicate with the new setup substituting pulley dimensions with gear tooth count to match your old all pulley setup setup or change as suits you. There are ratio calculators on the web as well or you can pm me with the metrics and I'll work up some numbers for you, but I figure what you were running is close to what you will be satisfied with. A great bike deserves a no slip setup for sure.
Rick C.