Transmission options for LS motors, any advice?

[Salty]

I am in the research stage of my build. I am reading many threads about high HP cars, race cars, and way crazy builds and realizing many of them do not reflect what I am looking to get out of this transmission.
Here is some background of what I have and what I ultimately want.
1968 Firebird, currently no motor or trans, 10 bolt GM posi rear end(think they are 3.73 gears). It is a clean palette so I want to chose wisely for my build by asking questions and doing lots of reading.
What I want to end up with is: 68 Firebird with modified suspension, brakes, LS2(or similar engine, 400hp or so), and a automatic that will reliably handle this 400hp. This car will be a daily driver for me 7 months out of the year so i don't need a huge stall but I do want to have some fun!
What trans would you suggest and what models of cars can I find this trans?
Is a 4L60E strong enough for me or should I just start with a 4l80E?
Any advantages to either of this transmissions?
Any thoughts on the 6 speeds that come in the newer G8s and such, are they decent?
Thanks,
Salty

[Salty]

I know some of you some opinions. Should I use a stock 4l60e, stock 4l80e, build a 4l60e, build a 4l80e, TH400 with a GV, or maybe a 2 speed powerslide? This will be a 99% daily driver that I will want to pound on occasionally but will mostly get driven. I am leaning towards a slightly modded 4l80e with a aftermarket torque converter.

[meenaggie]

For what you described I think a 4L60E, 4L65E or 4L70E that has been moderatedly built by any of the known transmission shops would be fine. I think a stall speed about 500 rpm above stock would be a benefit as well . . . maybe 2300 - 2500 rpm. All three of those transmissions have the same case and each is just a bit stronger than the previous when comparing stock GM transmissions. Once it is rebuilt by a performance shop you can no longer compare it directly to a stock unit. I don't think you need the 4l80E and extra parasitic loss that requires.