I use to have a XF Ghia Wagon fitted with a 351C, 302heads, 4V valves etc etc that was straight gas, don't run the 302 head without opening up the combustion chamber, not only does it give the starter a hard time, LPG in Aus is a mix of butane and propane, the mix is never the same and they have a big difference BTU and octane. Butane has slighty higher british thermal rating but far lower octane (cant remember but I think it is a fair bit lower than unleaded, dont quote me on it) and propane has a slightly lower BTU (lower than petrol) but much higher octane.(In straight form I think it is 100+)
But getting back to it, LPG may have a higher octane at a set temp but as a gases form that octane is lost with temperture, much higher than petrol as goes in as fuel droplets and changes to a gas in the combustion chamber which absorbs latant heat, lowering the combustion chamber temperture.
A shorter reply means, I wouldnt leave it at 11.5:1, I would bring it back to closer to 10:1or10.5:1, saves on headaches later, trust me I have been though it all, plus make sure you get go cold air induction, try to reduce engine bay temps as well, u will get good benifits from it.
Tuning is another thing, don't push the tuning to the limit, gas from one bowser to the next can have a big difference in propane/butane mix.
You can still get heaps of performance from it, LPG burns at a different rate so ignition maping is heaps different to petrol, normally more inital advance and less total in comparison to a similar setup petrol engine.
If you are a traveler get a huge tank as u already know from the other cars u have, in QLD other than the coast it is far between servos that have gas and their hours opened are short!
also, this set up is in a zk fairlane, you might be interested in the way i have my twin gas tanks
I am interested Execjim!