The 42 will have a 216 engine, which is actually a couple of inches shorter and has a slightly different design than the engine in your truck. I'm sure that a lot of the older ones ended up with later model running gear over the years just to keep them going, but a lot of adapting would be required. If you choose to go that route, swapping the entire drivetrain would be the way to go, and doing whatever adapting is necessary to make the later running gear fit the older frame. The 42 will also have hydraulic brakes, so the brake system would require a total swap as well as the engine, trans, and rear axle. It might be possible to adapt the original front axle to hydraulic brakes- - - -not sure of that, however.
Hang in there- - - -and get busy- - - -the work won't do itself!
Jerry
