Question on Bed Replacement 71 GMC 2500 Custom

[beaniid]

Hi all,
I have a 1971 GMC 2500 Custom with a Knapheide Utility Bed that has been in my family since the year it was made.
My grandpa and I recently overhauled the engine and carb so the powertrain is all ready to go.
I am looking to make this more of a daily use vehicle by replacing the utility bed with either a fleetside or stepside long bed, but as I do not have experience with this task I was wondering if anyone might be willing to give some advice on the following questions:
1. Is this a very difficult task to complete? (ie does it require drilling the chassis or having to do extensive changes to make a new bed compatible)
2. Where is a good place to look to purchase a bed to replace it with?
3. Do I have to get a bed from a 2500/C20 or can I use a bed from a 1500/C10?
Any other advice, tips, or any comments are welcomed.

Thanks,
Brad

Forgot to mention, I live in Utah, Truck is in Idaho currently.