I never lost to a RD 350/400 even when the airmen from Vance AFB on the radically modded bikes wanted to play. Mine was stone stock back then. Cosmeticly I'll change it a bit. A Stage I job on the jugs (though for extra $$$ I could get it schnurele ported.) It pulls like a tractor and wakes up when it get's on the pipe. Modern tires and some fiddling with fork springs and oil will change handling for the better. I'm cleaning the fuel tank with electrolysis and will use the same on the crank.
-- Keith