nice write up, i have lpg kits on my beetle and camper. one uses the little heat exchanger welded into the exhaust and the other is pre heated by engine oil. i personally prefer the exhaust method but the people who make the kit switched to the oil heated version as they think its safer, needs you to full flow your engine in some way though.
i wish id installed the kits myself now, although i wasnt quite as experienced at the time we had them fitted. they are so simple though and have really served me well. i would highly recommend using lpg on your aircooled to anyone!