I echo the above sentiments. I'm in the process of a frame-off on a '49 4400 and considered dropping a Cummins into my truck. Ive since dropped that idea.
Remember, most things that apply to half-tons don't to the bigger trucks. Completely different frame. The brake point above is a good one. Also, don't forget the rear end and tranny. That El Dorado tranny won't last long pushing that big truck around -- it's a car tranny, after all. And then there's the rear axle. It was designed, built and stressed for the 216/235/ babbitted straight sixes. Dump all that torque from the 500 into it and you will go faster. For a little while, anyway. You'll either destroy the rear axle or over rev the motor.
There's a reason you don't see hotrodded big trucks around (and they seem to be much cheaper to get than the pickups), and the ones you do see are old truck bodies mounted on late-model RV or duallie chassis.
Step back, take a deep breath and go hotrod something else.
Big trucks are best left to enjoy life in the slow lane.
Regards,
John
