I have seen a big block in an AD truck and since I've seriously considered doing it myself I've looked hard at a couple of them.
Using the stock frame and suspension steering is probably your biggest challenge. I've studied one 1/2-ton with a big block that used stock frame and suspension and it used one of the power steering conversions that puts the steering box ahead of the axle.
The others I've looked at did not use the original suspension, and the one I've had the best opportunity to study using a subframe swap, not something you would do if you want to use this truck as a big bolt.
I think you can solve the exhaust problem by mounting the motor a little higher. Often motor swaps on these trucks put the motor lower than it needs to be, which complicates some issues while solving others.
