The problem with the 3600 trucks is that they have a larger king pin than the 3100's. The bad part is that pretty much all your aftermarket kits are for the 3100's. You may be able to get a machine shop to bore and bush the axles to use other spindles or if you can round up a 3100 axle and swap the whole works, you're in the ballpark. Then you would have a lot more options.
