I'm running higher compression in mine - in fact, it's on gas because the original heads had so much milled off them, that it pinged it's head off on petrol, even at 6 degrees advance & light throttle.

We've had a string of dual & single-fuel gas cars through the family, and the sad thing with the 308s is the carby dries out when you're on gas, and if you don't keep running petrol through it on a very regular basis, then it stuffs up easily. With a carby motor and a points or HEI dizzy, you really need to tune it for one or the other - everything else is a compromise. Electronics with dual spark maps helps solve the ignition issue, but can't compensate for compression - gas loves compression.

And you don't have to have an ugly engine bay. With a bit of thought, it can almost be hidden - especially if you're running a factory aircleaner. I've mounted the convetor on a bracket I made to sit where the coil normally goes. The heater hoses run up the rocker cover (like normal) into it. The lock-off is mounted on the back of the convertor bracket's support (which is bolted to a bellhousing bolt) and I run a (certified) flexible liquid feed line down the trans tunnel - bolted in with P clamps. It allows for engine rock & movement. If I sit a factory air cleaner in place, you can only just see the back edge of the convertor.