The 1970 swinging arm is on solid bushes, I dont know if they fit the earlier arm, maybe they could be made to fit?, someone will know, keeping it stock is easy, the rubber bushes work well.

71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod