Rebuilt 904 w/ tf2 shifting woes...

When in doubt; disconnect the trans linkage at the carb, and just tie the KD lever all the way back; then go for a ride. Until you internally adjust something, this will produce the absolute crispest/fastest/hardest shift, and at the highest rpm,that the trans is capable of delivering, in it's current set-up.Make sure you can feel the spring-resistance.
Oh yeah, wind it out some...

That's the best advice on here. What if your trans goes ahead and shifts early even after you've set it up like AJ says? Then you know you have an internal problem. You need to stop thinking that you're going to try some new thing and it's going to work. Begin by troubleshooting.