What truck/engine are you considering for conversion?

I have a '68 F100, 390+4speed, and would love to convert it to propane or dual-fuel. However, the kits seem to have dried up completely in recent years.

Five years ago, I heard about a guy in Sacramento CA who could provide parts and perform the conversion for about $1400, but I didn't follow up at the time. Would love to hear about any kits you find.