Pimp my transmission

[PASD U]

Transmission help. Form letter.

Hate to do it. So I've finally come to grips with having to ask for help (x's 3 now).
I don't like it BUT...the alternative is experimenting with expensive components. Too much money.
I'll try to make this as short as possible to prevent any attention span issues. I had this posted somewhere else (deja vu) but may have painted TOO broad of a picture. I'm looking for suggestions for a transmission to fit my style. (something like a leather running shoe...haha j/k)
Keep in mind I'm new at classic American iron (sue me, lol) but not new to cars.
Feel free to dumb it down as much as you feel needed, I'll speak up if you're making me feel TOO dumb.

The car (65 Chevelle) runs a TH350 as of now. Uninspiring to say the least. Reminds me of an old truck the way it shifts.

Where I want to be: 90% Sporty Cruiser, 12's or better , 450-550hp for arguments sake.

Considered Bowler and TCI for programmability...$$$ 4l60e,4l65e,4l803, etc., who knows...

12 bolt soon to come in place of 10 bolt. Considered Currie or Moser, but not sure about gears.

What transmission and Why and from who? I really need an explanation here. Opinions are fine but mostly facts to improve my knowledge about what I'm doing.

If I AM able to run an electronic transmission with the 327, will I be able to utilitze electric gauges. I hate the bouncy mechanical gauges.