Ha, Gary, awesome job spending that money!
I guess my point is: there is no NEED to spend that much money, and no "justifying" it other than just that you want to.
I weigh 220 lbs (BLUSH) at the moment and a stock engine will pull me around fairly well.
Mind you, I have to pedal a bit on hills and starts, but that helps solve the weight problem...
Case stuffing, a larger sprocket and head mods will give some low end torque for those clutch starts and hills.
Porting, pipe and modifying the stock head will give power and speed (more rpm).
A look through the archives will outline details. (Gary is a big contributor)
For those who are new to this sport/hobby, no need to spend big bucks.
And these engines can last many 1000 miles, but not if you mod them for max power and rpm.
I'd suggest a good air filter and good quality oil and daily maintenance are the recipe.