I am considering replacing my throttle body 7.4 with a 8.1 short block. Need mope power for towing.

Has anyone done this there looks to be a few more things to consider than a simple bolt on the heads and go.

The head bolts are a different size, probably have to drill out the block to bigger size for 7.4 head holes.

Using nv4500 manual trans, which flywheel works?