Yes, you can get pre-made governor weights and springs (I think there's a spring involved, can't remember for sure). The governor is in the tail housing on the output shaft. It's not in the vb. It controls shift timing and line pressure based on driveshaft rpm (changing rear gears often means the governor needs to be tweaked). If I remember right, there's quite a few choices so I'd call the vendors to see what they suggest. Fine tuning is often needed but it's not too hard based on what I remember.
Yes, by throttle lever I mean the kickdown. Specifically the kickdown lever on the trans.
