So, do you want to know about an 87 or 89? 87 stay away, 89 in good shape I'd probably jump on it, I had one brand new. The forks were still right side ups, but man did they work good. Motor parts are pretty much interchangeable with 500's up to 04, I think the 89 still used the older style flywheel, much lighter than 90 up, good bike, realizing it's 20 years old I'd still buy it if it was in really good shape.
good luck