I've noticed that with the larger trucks (i.e. 1 1/2 ton and up) that they are typically driven different than the 1/2 - 1 tons. When higher velocity is needed, the foot goes all the way to the floor, the carb opens all the way, the engine is providing max torque (for that rpm). When the desired speed is reached, the gas pedal is let up on to maintain the desired speed. In these cases the weight of the truck is so large with respect to the engine capability, that acceleration is always done at full engine torque.
Now think about a 1/2 ton short bed hotrodded with a 350, Holley 4, etc... If you put your foot to the floor every time you want to accelerate, you'll be buying new rear tires often from all the burnouts you do. With smaller trucks people tend to push down on the gas pedal proportional to the desired acceleration they want. Therefore in a smaller truck the engine is seldom producing full torque for that rpm.
An engine that is subjected to a harder life, i.e. 261 in a 2 ton, should be made stronger to last the same amount of time as a 235 in a 1/2 ton. I think that is why the 261 has some stronger components, but specs out similar to the 235 in torque output.
Now what do you want from your engine? Put the rebuilt 235 head on the rebuilt 261 engine, dump it in a 1/2 ton and it'll be a hot engine in comparison to the stock versions, and the head will probably be sufficient for non racing driving. Dump in a offset grind crank, over bore the cylinders, hot cam, increase rocker ratio, port and polish head, headers to a dual exhaust, triple rochestors or 500 cfm Holley, etc... In this case beefing up the valve train sounds like a good idea to me.
All this being said, I've got my eyes out for a junk yard 261 to rebuild (with the 235 head) and drop in my 58 1 ton.
My $0.02.
