Make sure you check out JACAR's parts listing.
http://www.jacarmotorsports.com/store/ (Highly reliable and reputable source for parts including MRP at a fair price, but the site needs more detail and descriptions of parts and applications)
Links to other sources can be found at...
http://www.mrp-speed.com/store/home.php?cat=260 (wholesale only, but gives you good ideas of what to look for at dealer sites)
http://www.oregonvintage.com/Scootparts.html (Good source for MRP parts and excellent links to articles on installation and reviews)
Good Luck!