Propane has fewer BTU's than gas but a higher octane rating. Around 100/110.
Very popular full conversion in the 80's. To offset the lower BTU's raise your compression 1 to 2 points. Propane burns very clean. I have two propane powered forklifts at work. Oil will stay clean for a long time.
If system is done right and mods to engine you'll have no problems.