I want to install a rear disc on my mint condition 1984 XR 500. Some say don't be an idiot but has anyone done it? I realize the parts that are needed(swingarm,linkage,shock,wheel,caliper, master cylinder,pedal) but which ones will fit?Ebay always seems to have a bunch of parts so supply doesn't seem to be a problem. The bike already has a WP front suspension and Magura brake on it, so I don't have a problem with doing some fabrication to make the retrofit work. And no, new shoes are not the answer, we ride in the rockies and shoes generally last 5 or 6 rides. Thanks for any help.