You will love your converted Firefly. I have a 1991 Geo metro with a 9” Advanced motor FB1-4001 running on 45 Lifepo4 cells. It’s been my daily driver for 4 years now and I love it. I just put in 3rd and go on surface streets, shifting to 4th for the FWY. You should be able to do the same with your 8” motor also. About motor brush timing, at higher voltages(96V) it is done to keep the brushes from arching. Check out the attached EVDL post,
[EVDL] Advanced Timing speed/volts chart, best setting for daily driving - DIY Electric Car Forums . My motor was shipped with neutral timing. I removed the 4 bolts holding the end bell on and rotated the bell to line up withthe advanced set of holes to advance the brushes.
Happy Motoring
Joe