Inliners International Forums General Discussion Hi Performance Dual Fuel System

I'm interested in a system for the '67 K/10 Suburban, that would run on propane primarily but be selective to run on gasoline when needed. My friend tells me this is not possible w/o changing carbs, jets, blocking off fuel lines etc. Too much to do on the roadside or in the dark. I thought a dashboard-switched sytem had existed since the mid 1960s. Is he correct that switch -on -the -fly is not possible or at least very expensive to configure?
Currently there's a 454 V8 in the rig, but I'm thinking of rebuilding a '63 292 L6 @ .030-over w/propane pistons...