I had a twin throttle body gas research setup on my old XY ute and it, once tuned correctly had more power than the holly that was on it. It had the same fuel comsumption but was half the cost to fill up.
Allot of people run turbos on lpg as it cuts done on a few items like fuel pumps and regulators. This is cause the LPG is stored under great pressure. GRA (GasResearch Australia) do blow through and draw through setups to suit most applications.
Putting LPG on a 1200 would be so sweet cause thay are so economical already, the only downside is the initial cost to set up (although you will be refunded $2000 by the goverment, EVENTUALLY) and the other possible down side is the size of the LPG tank and fitting it to the vehicle, our cars, even utes are limmited on space already.
Another option is a company in Perth have developed LPG ELECTRONIC INJECTION using special LPG injectors and some other stuff, very cool, lots of tuneable power to be gained and half the price unleaded, what more do you want