Mines a 83' and I had a tough time getting them without paying $120+ for a front and $140+ for a rear. I got my front which is a K177 off the Craiglist, its a 18" front for $60 new shipped. The 16" rear I got from a guy on ebay and its a Metz with less than 300 miles on it for $75.It was off a bike with a fried engine the guy parted out.
I ran a set of Maxxis Classics but they got harder and harder to find a complete set. Don't know what I'll do when these wear down. I have a new set of BW for the bike. May just have to use those.
Darn WWW are getting tough to find. Just not many for my 16 & 18" rims. You'll have better luck finding the 17" and 19" than what I had .
The PO had a K177 and a Venom when I got it. One set of WWW I bought from TiresUnlimited. Those where the Classsics from Maxxis. Cheaper tires and didn't last as long but I got about 12k out of the front and 10k out of the rear running Dynabeads.