I'm no expert but i do run a big block n my 40 1/2 ton and it seams to fit pretty well.
The firewall needed a recess for the valve covers to clear at the back corners. I chose to leave the majority of the original firewall in place and created two "pockets" for the valve covers.
I used fender well headers to clear the steering box, which meant my inner fenders needed to be modified and the rear of my BDS style scoop needed to be "flattened" due to my tunnel ram height. I was also forced into using a Suzuki samurai alternator due to where I wanted to place the alternator.
Take lots of measurements when placing the motor mounts and include as many of the engine accessories as you can... mine ideally could have been 3/8 of an inch lower.
That truck is pretty sweat as it is... I'd cruise it just as it sits
