The GMC motor is longer and that does present some issues. Read the tech tip I referenced it will tell you most the details regarding length.
The PTO, clutch and driveline should all be easy. Tougher might be accelerator linkage, but if you can simply swap to the GMC stuff you should be fine.
There are some aspects of a '47 that are different than the '48 to '53 trucks and I'm not an expert on those details.
