Murry,
More on the 4L80E. Like Craig said they are beasts. 1500 HP is a walk in the park for them. They are astoundingly reliable. You can get valve bodies for them that are full auto, full manual or auto with a manual shift option.
The guys over at Hughes Performance in the states do a very credible job with them. Here is a link for them =>
Hughes Perf 4L80E
Ed