Re: cruiser frame, but replace front fork with shocks?
RST makes a bunch of forks with 1" threaded steerers. No one else does anymore, but you might find an old Marzocchi with the replaceable crown and get a 1" crown, or find a springer with v-brake.
I have a Schwinn Avenue with the 700c pogo stick fork (no damping, no oil, just grease and springs). It works nicely as a pedal bike, fixing to find out how it does on a fric-drive bike. It seems pretty solid. I have used this as a cyclocross/mountain bike for 1 year.
1" roller Dax Friction Drive and Tanaka 3300 with mods.