Howdy folks, I have a Trek 500 (84) with the wonderful Malliard Heliomatic. Since it will fail and they're tough to get parts for upgrading is inevitable. How tough is it to swap over to 700c wheels?? I realize I'll need to do something with the brakes, whether it's a simple adjustment or a replacement, we'll see. Are there any other things I need to consider? Thanks for your time JT/Edmonds, WA