Changing gears questions

If you're going for the A727, personally I would go for 3.73, maybe even 3.91's. Especially since your're trying to hit the 12's.
However, if you can I would look for a close ratio A904's and beef it up or better yet an A999. And then stick a 3.55 gear, that should get you close. Or you can rebuild your A904 with a TF2 kit and beefier internals, not sure about this but I think you can also put a close ratio setup in your A904.
A close ratio with 3.55 gears will act like you have 3.91's in the first 2 gears.

That is what I have, I have a 360 with 9.7:1 compression with rollerized valvetrain and camshaft. Mated to a close ratio A999 with TF2 kit. I have 3.23 gears in it for now and this thing still can book-it if it wants to.