"would i be better off with a worked 235?"
I can't answer that question without knowing what your expectations are for your truck.
From what I've read so far, your truck is a cobbled up pile of parts. The torque tubes are all different lengths. That makes it very difficult to use one from another model as that may require you to move the engine forward or aft to mate up to the torque tube. Moving the engine forward puts it into the radiator, and moving it rearwards puts it in the firewall.
My reccomendation is to use an open drive rearend from a 55-62 chevy, or even a later chevy 4wd 12 bolt rear. You could then decide on a engine/transmission combination. The 235 is a good motor. The 292 is a better motor. The 235 would be an easier swap, and would work with the original transmission and torque tube, which I suspect are long gone.
Prewar trucks used the bellhousing to mount the clutch and brake pedals. A 1939-1959 gmc 6 or a 1937-1959 chevy 6 will all bolt up to the original bellhousing. Not sure if the GMC motors are available in OZ, but they are better than the chevy motors. They are also longer, so the radiator would have to be relocated forward. If I were in your shoes I would be looking for a 235 or 261 chevy motor to use with a 37-47 bellhousing. A 49-54 bellhousing will also bolt to the engine, and to the crossmember. The 49 and later bellhousings are setup with a standard Muncie bolt pattern, allowing the use of many transmissions like the t5,saginaw 4 speed, muncie 4 speed etc. The 49 and later bellhousings will not bolt up to your clutch and brake pedal assembly unless modified. Jim Carter and Buffalo enterprises sell a modified bellhousing to accept a more modern transmission.
