That is a tough one. Has it been repainted? It's a touring frame and the serial number would indicate a 1988 model. No touring model that I know of came with cantilever brakes in the rear and caliper brakes in the front. I suspect that the fork was switched at some point and the frame repainted. The only 1988 touring frame with cantilever brakes was the ST1000, so that's what I would say the frame was. The Sansin/Wolber 58 wheels were used on the 1987 ST800. It's possible a dealer built it up from various parts. What are the other components?