If you have worries about valve seat damage from lack of lubrication with unleaded,add a couple of capfuls of Marvel Mystery Oil to the tank before every other fill up. As a sidenote,it seems to improve the octane of the gas by about a grade. I don't know how it does it,maybe it "fools" the engine into thinking the octane is higher,but it enabled me to run regular no-lead in my old Harley FLH,when it used to ping with anything less than 90 octane.
Speed


1954 GMC 350
1957 GMC 1/2 ton
1962 Chevy C-30
1952 Chevy 6400 dump bed project truck
'98 Harley FLSTC
'66 Pontiac Catalina
'76 Chevy 1 ton Duallie
'84 Bronco II
'78 Dodge W-200
'81 Toyota 4X4 truck