Here is a set of 1992 forks that will work for the 17" front wheel mod on the '84-'87 FJ's. The price looks very good.
If you are on the fence about doing this mod. The late model forks do not come up for sale very often and usually in the price range of $250.oo and up.
http://www.ebay.com/itm/1992-92-YAMAHA-FJ1200-FJ-1200-FORKS-SET-/231713755280?&_trksid=p2056016.l4276#ht_3823wt_758 (http://www.ebay.com/itm/1992-92-YAMAHA-FJ1200-FJ-1200-FORKS-SET-/231713755280?&_trksid=p2056016.l4276#ht_3823wt_758)
Fred