Did run the 360 engine in my 73' j4000 on propane with a impco kit as a daily for thirteen years.
And also run on highway speeds on hot days.
Did run it a couple times overheated when the radiator lost a lot of cooling fins.
It was a good used and sometimes abused engine ,but never gave me trouble with a head or head gasket.
It finally stopped running on all eight cylinders and after a compression test it barely had any compression left , so parked the truck before destroying the engine.
Later on pulled the engine and I'm now working on it to have a Cummins 12 valve diesel engine.
Jeep "because mother nature hates flat roads to"
99' Dodge ram 2500 4x4 crew cab 5.9 Cummins ,backup work truck for now
73' Jeep J4000 (named Heep or Desert Dragon) amc 360 V8 converted to LPG with T15/D20 (was my daily work truck for thirteen years and is going to have major overhaul
80' Jeep cj5 350 V8 Chevy/sm420/D300 project
70/71 Jeep J4000 parts truck with Buick 350
Trucks/car's from the past:
85' Volkswagen caddy mk1 1.6 diesel.
83 Toyota land cruiser BJ42 3.4 diesel.