Gasoline fuel injection > propane. Regular old fuel injection will run at any angle. Propane is a pain in the ass and probably the most expensive possible way to run a rig. Also, you can't just "Run down the road." for fuel like you can gas.
The TBI system is simple and reliable. Put your ECM in a old ammo box, seal wire hole, run a remote vent tube ('puters get warm). and you are good to go. TBI is butt cheap, propane be the opposite.