RS250 5.25" rear is the easiest to fit. As StephenRC45 says you do need all the HRC gubbins to go with it, but than can be sourced. Well some of it can. Or fabricated.

I've got TZ marvics in my bike. Rear's 5.25". It was an easy fit, just so long as you have a machine shop at your disposal

Front 3.5" rims are common on NC30/35 and bolt straight in. They're not Magtek's though. If you want magnesium wheels you'll need an RS front. Pretty much plug 'n' play, but will need a front spacer change.

If you have the knowledge, the time and the tools you can get anything to fit within the boundries of common sense.