There is precious little travel on the rear Shocks to start with, reduce that by an inch and the shock will be bottomed out most of the time

BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
GM500 sprint bike "Deofol"
Rickman Jawa 500 "Llareggub"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro No Senshi"
Kawasaki Ninja H2 "Fujin"