The '88 frame is completely different from the '87, with virtually no parts interchange. There's going to be a few issues using the GMT400 ('88-'98) chassis, as it is somewhat of an oddity. One issue will eb the frame width, as it is actually wider under the cab and forward bedmount area, then tapers back to the rear end. This was one of the reasons that you don't see factory Chassis/cab version of that body truck until the '92s, aftermarket bodies would not fit the frame.
I won't say it "cant be done", but only that you will need to get your measurements from both the frame and the body and plan out how you're going to make it all fit. You may have to make some concessions and alterations so it will work.
