I think the cam is pretty close myself with a 4 inch crank I would not use that 218 duration if it and the 230 were my two choices much smaller it will be out of breath before it reaches much rpm I realize its being built to tow with but it wont be towing all the time more than likely plus it will still have plenty of torque to get going not like a Cummins does but when its rolling good I would think it would give a older Cummins all it wanted as far as passing someone rolling at say 55-60 mph. I have owned a older Cummins good tow rig plenty on the bottom but not a speed demon when it was rolling good that 4 inch crank makes a huge difference in a small block. You should have over 400HP I would think and close to 500 ft lbs on the torque maybe a little short of that but I would say close.
A 4 inch stroke small block tows just fine in my opinion hell it has more stroke than a stock big block 440 has and they use to be the rave supposedly for towing before all the diesels came along I think we have got a little spoiled with the power the diesels are making now but it sure doesn't mean that a 4 inch small block cant still get the job done I assure you it will if it has a good cooling system.