If the front brakes are the major hang-up for you on the XL600R, its an easily rectifiable situation. I just did it on my XL600. I got a front set-up off an RM250 (a modern one) that uses the same basic Nissin brakes (uses the very same pads as the XR650 L and R, CRFs, TRXs, RMs...countless other bikes) but the caliper and master cylinder is a more up to speed design, as in, its works. The only thing that needs modified is the bracket needs clearanced a tiny bit so the rotor bolts dont hit it. All I did to clearance the bracket was used my el cheapo Harbor Frieght bench grinder and held it against the outside edge. It was almost the same diameter as the rotor bolt pattern. I removed just enough material as needed. I have already rode the bike. Nothing hit (I did check before taking off) and the brakes work great!!!