The 165 would have to be custom built. I have considered it and there are a couple of ways of doing as to where you graft what to what.
I would probably opt for a fairly rotten 164 base car and just you the bulkhead forward from the 164. Rear end I would go for a late model 240 as they tend to have the least corrosion issues. I might considered changing the rear lights to the 145 style ones but that is just down what the builder prefers to use.
I would stick with a B30 and probably the E engine for power with either a manual box of find a 4 speed autobox to use. Again like you it would be LPG powered.
If you are happy to go with a 145 there is a very nice one for sale here
http://www.volvoforums.org.uk/showthread.php?t=192931
It is manual but converting to auto is easy enough. I have a spare gearbox available and the other bits needed to convert if you were going that way.