I cannot answer your exact question, but perhaps my experience will be of help?
Some years ago I fitted the kickstart and decompression mechanism to my 3AJ. All the parts came from the previous 1VJ Tenere model. The one part that would not fit was the decompression cable, as the outer cable casing & end was too fat/broad to feed between the bottom engine casings. I found that a late (2000) TT600's cable was much thinner and fitted okay.
I am guessing, but I think an early TT600 (e.g. '83) engine casing design would be similar to the 1VJ and have a broader decompression cable casing. While the later TT600 had a 3AJ type of engine design.