l read your post before we put any more parts in truck l think we need to go back to basics first disable the spark than pull the spark plugs all 4 of them than open throttle and install compression tester in each cylinder and see if you have enough compression to start this engine it takes a minimum of 90 psi to fire a plug but l would like to see about 150 psi in each cylinder at about 3 to 4 cranking revolution if that checks out than let's see if it fuel or spark sometimes it can be hard to tell. next put the plugs back and the spark if you don't have a way to check the propane at the primary plug in the emco converter l would undo the propane tank and release the pressure in the r ego valve try to spray a small amount of starting fluid in air cleaner and see if trucks starts if does you know you have fuel problem converter fuel lock or carb diaphragm. if still will not start l would look for spark check to make sure when you put dist in truck you have put in same spot as old dist this moter has teeth on Cam and dist could be off a few teeth when you put back in might have to put a top dead center and drop back in again check firing order again 1342 next you said you have weak spark make sure you have battery voltage at coil l believe this truck uses ballast resister before coil if so one side should have battery volts and drop on other side of ballest make sure hooked to positive of coil.next you said battery is good l have seen a starter dragging down causing low voltage to ingion and week spark check to make sure you have approx 10 volts when cranking to start an engine you need 3 things spark fuel and air hope l was of help also l think by model this truck has 4g 54 moter in it

That girl should have a the Mitsu 4G63 engine. Old school Impco fuel system? How did you determine you have fuel?