I reckon the KX500 (SR500) and the CR and RC500 Hondas up to 1990 do all but fit in the vintage scene even if.
Unlike the new generation 400/450 4 strokes the KX's and CR's didn't change all that much and up to alloy spar frame models they wouldn't look out of place in pre'85 grid. Maybe I am a little ignorant of these models but to me from about '85 - '90 there was little change with the open class 2 strokes
or was there