If you want the original, fusible link type, they are still available. Check with your local Honda Service Shop, or any motorcycle service shop that works on Honda's. Like Tools, I converted to an ACM type fuse holder, $5 at Wal-Mart. I just crimped on two ring holders to its wire ends, and attached them in place of the fusible link, under the side cover. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII