Interesting question

I think a genuine NSR would still be cheaper, handle far better and more importantly be reliable

And when your finished all you’ve achieve is a mongrel / faux that would be hard to sell on and never get close to returning your investment.

And without being rude a 500cc single isn’t a replica, it’s a whole different beast
Personally I think you’d be better of putting an RD350 motor in a TDR set up