It would perhaps have been wise to have had the crank rebuilt and balanced etc. before pushing more power through it. Cranks are a service item, they don;t just spin forever without attention.
I reckon you should fix up the NSR. Do it properly and it'd give you far more fun and satisfaction than the Gixer ever will. The occasional engine blow up is inevitable (on any bike) if you push them a bit. Fixing them up better than before is an important part of the fun and satisfaction in my book.
Wb