make it new or leave it alone ?

I'm biased , I have always liked original cars at least in terms of paint and wheel sizes.
I wouldn 't consider painting it , just polish & wax. I'd look for improving the interior, I'd take my time & try to find used pieces that are in better condition, there's a lot of donor cars out there.
I would also avoid the urge to go for more horse power but make sure the safety stuff is good: brake hoses, new tires & steering.
If you really want to restore one there are better candidates but you 'll be financially upside down almost immediately.
Very cool car an original condition Demon with a V8, AC & disc brakes - that's just about perfect