Haven't checked the forum in a long time so I've only just read this build diary.

A Tz85 will run a scooter motor no problem, I've used one in Hatchet before and it was fine. With regards to the Victor, Hatchet did use one for 2 years and it was fantastic. They're difficult to find now though hence why I swapped to a Tz85.

What reduction and chain pitch are you using btw? Hatchet now uses 8mm pitch chain on a 10:1 dual stage reduction, earlier versions were a single stage 5:1 reduction.