You can shorten your wheelbase like dieselcruiserhead did, or stretch you body. I was looking at stretching the front door. Measuring my 80 against my 55 showed that's where the 5 inches of difference went. If there was something about the 55 body I would want to change, it would be the small doors.
You also probably have to move your drive train, or move your cooling system like Waggoner did. The 80 engine sits about 5 inches further forward in relation to the front axle.