So your target rpm is 8200-8250. My first choice is a 48-44 and 46-42 full , both angles are on the same helix. Two springs I would have on hand 140-220 and 155-222 with the track ur using. Start off with the 46-42full ramp and 140-220 spring. That track will load the secondary, which will load the motor, if the 140 is to weak, put the 155-222 spring in.