Im quite sure Suzuki used the gk73 in the series too, somebody on the PS facebook page posted a picture of a pretty trick looking gk73 claiming it was a TT-F3 bike, will try and dig it out to be sure.

Edit: Found it, apparently its Doug Pollans 1988 TT-F3 GSXR400RRSP. Makes a change to see a bike in this thread thats not made by Honda

Dang! Looks pretty rad. Wish I had a GK73.

It seems like its easy to turn up TT-F3 pictures and info about stuff before the 90s. They show a version of a gk73 race bike in the suzuki promo video for the 1990 GSXR400 you can find on youtube, where Polen is the spokesman, and he just hams up how good the gk76 bike is.

Yea it does look pretty smart, nothing like a road going gk73 though. The bodywork looks like its from the gk76, apart from the seat unit. I think i have seen that video is he on a track on a blue and white gk76 thrashing it round? And yea he does go on and on about how good the bike is if i remember.

Found what looks to be a press release of the NC30 on youtube, small piece about the F3 bike in there which could be of interest.

http://www.youtube.com/watch?v=AMPsyJYgg5A

Suzuka 4 hour results:

1987:

1988:

1989:

1990:

1991:

1992: