Having more experience with gas engines than diesels in trucks myself I've seen far more damage caused by a 250 HP big block than any 500+ horse small block could ever muster.
500+ lb/ft numbers from naturally aspirated small blocks are made with fudged dyno inputs. Even if it were possible, small block power is different. It's peaky, useless in the real world.
Build the nastiest small block your wallet can muster, put any tranny you want behind it and any rear end ratio. Put it in a 7000 pound truck and tow a 10K trailer up a steep grade for 20 miles at 65 MPH. You won't make it.
Drop an RV cam in a low compression 4" stroke big block with headers and a small 4V. Put a 4 speed behind it and 3.55 gears 31" tires. Put that in the same truck and do the same thing. You might have to hit 1/2 throttle to pull that. The engine will sound like it's in it's sweet spot at 2500 RPM even with all that load. Everything will seam normal, except maybe the driver's side of your hood sitting up a bit from engine torque.
That's torque. Torque rips trailer hitches off frames, turns 1350 U-joints into powder and accelerates heavy loads without downshifting.