Propane-powered big block GMC

[72_gmc_suburban]

I'm looking at a 70 GMC, 1-owner C20 truck. Everything seems great with the truck so far. Little/no rust (it has lived in the southwest its whole life) and nearly all the available options for that year. (no tach, no sliding rear window, but everything else) He also has full documentation of the vehicle's history.

The only question mark in my mind is the truck has been converted to run on either propane or gas. I know *zero* about propane-driven vehicles, so am turning to here for help.

The truck has 230k miles on it and, according to the owner, ~80% of that has been on propane. Is this a good thing, a bad thing or pretty much indifferent? Anything special/unique I should look for when I inspect the car tomorrow? Anything to be aware of specific to propane-driven vehicles?

Thanks