If the '94 hasn't run for several years how confident are you that it's good? 43K in a motor home can be rough duty, depending on the driver and terrain. The ECU would have controlled injection and spark, and maybe the transmission. To eliminate you'd need a new intake, carb & air cleaner for sure, and if the tranny is electronic then you'd likely be looking at a stand alone tranny controller, too. Could be a practical solution, if it's a good engine & tranny, and hasn't suffered in storage.