With the addition of the disc brakes, the factory wheels probably won't work either, the center section of the wheel may be too close to the caliper.
I helped another guy out with a 41 doing his ball joint conversion deal, but he also made his own mounts for a cavaliar rack and pinion . Pretty much 37-57 is the same basic design suspension, although 37-48, 49-54 than 55-57 is how I would group them individually because of certain differances. But I would try to find an original set up first since your keeping the rest of it stock.
http://crankshaftcoalition.com/wiki/...ing%22_to_Rack
Just keep in mind, this article only applies to a 41 that has already had the ball joint conversion done with dropped spindles. It just gives you a basic idea if you ever decided to do this.