You can change pistons & rods in the NC1 motor to the later NC2 ones.
NC1 has heat fitted wrist pins ( the rod and piston need to be purchased as an assembly )
NC2 has floating wrist pins retained by circlips ( you can buy rods and pistons separately )
Some of the engine reconditioners fit the NC2 rods and pistons in to the NC1 engine.
However - if your quest is big power - the NC2 engine has a forged crank and forged rods to make the bottom end stronger.
When you consider that a forged crank is appx £900
NC2 rods are appx £125 each
NC2 pistons are appx £90 each
Starting your refurb with an NC2 motors it probably more cost effective.