This has been a topic that I have struggled with for years. In the early '80s my Dad bought a '34 Chevrolet Open Cab firetruck. It took on the project of keeping it going and maintaining it. We kept it just over 20 years before deciding it was time to move on. It went to a good home and is still on the road here. This winter I purchased a '53 6400 firetruck. My first thought was to take off the firetruck body and put a stake body on it. I've had some second thoughts about it since. The "shock & awe" of a old firetruck going down the road can be priceless. The down side is the limited uses for the truck in its original state. The last point is the costs involved and the amount of work to preserve and maintain just the firetruck stuff can be costly and difficult. So, I'm still doing some soul searching and trying to think things through both ways, but in the end whatever the decision is it will still be 50% wrong - unpopular with the masses. You need to decide what "you" want and desire and make a plan and move forward.
Good Luck
Don