tranny questions

[silverbullet94]

I have a 94 gt all I've done so far is 2.25 headers back and a short ram. You guys probably know 75mph and 3600 rpms is kinda ridiculous, that high os rpms with that exhaust is pretty loud which explains the exhaust ticket I have. The syncro in third is pretty bad and I want to get a whole new tranny. I'm thinking of putting in a six speed transmission from the newer celica's.
1) would it fit
2)Because the newer celicas rev higher would I not get peak horsepower at 5400
3)will I get longer, shorter or the same length gears
4)what would the top end be cuz I can only hit like 122-124ish due to lack of hp and being just about right at the redline in 5th (150 is the goal)

Thanks for the help

[hatchy_gt-s]

you may be able to switch bell-housing but thats a big if.