I don't know how much rust or damage may be on the rear of the car, but if it is as clean as the rest looks then that Monza would be a prime V8 swap candidate in my neck of the woods, the midwest rust belt. Make a nice light drag car or a street hotrod out of it.
Haven't seen one as daily driver clean as yours for 15-20 years, at least.
It was available from Chevy with a V8 so it's an known fit.
Hard to find not rotted to junk in my neck of the woods. Worth more than most any 25 year old Japan cruiser bike.
I say keep it and do a LS V8 swap on it.
If your into that sort of thing, just sayin'...it's one idea.