I think the rm/yz/kx/cr 80 to 125cc front ends should clear the front tire if you plan on using a bicycle front tire, but if your plan involves using the tire and rim from the donor bike it doesn't matter which bike or what size it is.
If you can get a set that's air adjustable you can soften or firm up the ride to better match you and the bikes weight, and if your plan involves using a 26" wheel you can add more oil to the fork tube to prevent bottoming out onto the tire.
Either way the braking and suspension will be great once set up. You may need to get the bearings and cups from the donor bike and also fab up some spacers to make it all fit, but that's gonna be the easy part.
Also, post pics if you do it, I was toying around with that idea before I found the front end I wanted on this bike, but I may build another soon and always looking for ideas....