I weigh as much as you- I'm all the way down to a 34 alloy sprocket in back- and still have to do almost no pedal assist- if I wanted- that's with a 66 two stroke with a short billet intake and 66 speed carb- I have plenty of power on flats here and cruise 25-30 on the speedo with the throttle about 1/2 to 2/3 open- which really gives a quiet and smooth cruise-
I also have a 50 build- 39 alloy sprock-not so fast- but REALLY lightweight cruiser and rides very much like a roadbike with 700c tires.
I'm from a road racing background so I like the bike to be as peddable as possible- The 66 is a cruiser with 27 inch alloy wheels- and I'm always shutting off and coasting or else just peddling in parking lots or near the retail places that are my usual destinations. Its' like having a regular bike with afterburners- I eliminate the motor tensioner with a derailleur and use a very lightweight great rolling 415 trike chain- so whatever a kit weighs by itself- I've taken POUNDS off with alloy sprocket, light chain and not using the tensioner. And I always use alloy bars and 3 piece alloy cranks and pedals.
I find the two cycle convenient and easy to use- I used to be a bike mechanic- so that's another factor- a four cycle is a bit more mechanical challenge and you usually need wide cranks-
on the other hand if you don't want to pedal much at all, , the 4 stroke may be better for you. And a bit more quiet I think.