P38A Range Rover Manual 4.0 scrapper with decent engine, preferably LPG

Currently I run an oil burner but if the UK government war on diesel continues I'm going to have to convert to gas or similar. I think the 4.0 manual is near enough a straight swap so I should be able to get it in there. Preferably it'd already be running on gas. No rush, just keeping my options open for future proofing. If there's one at the right price I'm interested.