Gullarm / Triarm NC23/NC29 uses different discs.
Theres a lot of front wheels that can fit relativly easy from bikes of that same era that use the same discs...
VFR750R RC24... CBR400 (Early NC23 / Aero Models, match the disc bolt pattern)
Forks are no no.. there 50mm too short for a start and there 41mm instead of 37mm.
Any fork option is going to be pretty pricey tbh (worth more than the bike) just get some stiffer springs and use heavier fork oil, with 11psi of air (geunine honda seals only)
Fork choices though VFR750R forks are 41mm and the yokes match.. there also the right length too..
CBR400RR forks are the right lenght, you'll also need the yokes... & you could use the NC30 legs to get the 4 piston calipers too

(combined with a CBR400 front wheel / discs)
You can get some half decent tyres for the bikes standard 130/70/18 / 100/90/16
BT39R are the sportiest Bridgstones you'll get
Is your dad outriding the BT45/39 or whatever tyres that are already on the bike?
A Dunlop Arrowmax on the front and a BT39 (130/70/18) or BT92 (140/60/18) on the rear is usually a good set-up for the standard bike.. still doesn't help the soft forks though