Ivan,
Having placed a healthy 292 HDTD motor in my Coupe was the best thing I did. I asked a lot of questions like you are doing now and came to the decision to do it. The old phrase,"there's no replacement for displacement" holds true in this case. Your Pickup will benefit greatly from the longer stroke and extra torque that the 292 has.
By adding just headers, 4-barrel, 3/4 cam, and an electronic ignition system, you'll feel and see a whole new motor! If your's is tired as you stated, do it right. Get the cylinders clean out, new rings, bearings, and a valve job and your pickum-up will serve you well.
I put a T-5 behind the motor and a 3:55 rear and get almost 20mpg on the highway! In town, about 14mpg. I also have great torque and acceleration plus I can pull long hills with no effort!
RapRap
1940 ChoppedChevyCoupe
