A Dr 70cc will definitely fit with a bit of shimming of the fins: 30% more power.
The following Reed Valve: Boyesen dual stage power reeds "MOD" for pa50, pa50II camino nc50 na50 nu50 will also be needed and will fit: Easy
As for the intake, the following intake adapter, coupled with a Mikuni Vm16 will fit without any major modifications. (a bit of shimming here and there)
You can also keep your stock air filter box.
Garelli VIP polini 19mm shorty PHBG intake
Thus, you can forget about the more expensive Weak-Ends intake:
WEAK-ENDS honda express NC50 NA50 mikuni VM intake
The beauty of the Vm16 model is that it small enough to allow to keep your stock intake, without having to ''raise'' it with a ''filler'' shim or to ''bore'' the intake hole. (they're actually the same width)
It's actually a perfect replacement carb for the Nc50.
This combo will leave a 1cm gap underneath to clear the rear break cable.
But this overall combo is a question of personal choice...budget...and desire to keep it looking stock or not.
Finally, you will need to up-jet in the range 85-95 to achieve full power.