the only difference is with a single point system it is very basic, the gas is introduced to the engine above the carb and is drawn thru the engine in pretty much the same was as petrol so you have a mixer plate mounted above the carb.the other type ( more seen in the US) is to have a plate that is mounted underneath the carb , the only difference is where the gas is mixed, the improvement with the second type is that there is less chance of the system backfiring, with the first type when then engine coughs it pushes gas back into the airbox which then ignites and blows the air filter houseing to bits. Most lpg suppliers should be able to provide a single point system,that will work on the cj