With your engine you will never get close to breaking a performance rebuilt 4l60.
With 5 pinions it becomes a 4l65.
And you would HATE a 4L80. The rotating mass is much heavier than a 4l60 and it will rob TQ and slow your Tahoe down.
I would run that with a turbo making 900hp, but under 600hp a 4L60 is fine.
Heat kills auto trans, so just keep it cool, under 200 always and it will run for a long time.
So big cooler, biggest you can plumb in there.
I've run these for 7 years in Tahoes, Escalades and Silverados
Cheapest transmission saver you can buy.
Series 9000 Plate & Fin : 17 Row Series 9000 Plate & Fin Transmission Cooler Kit (derale.com)
With this its always under 200, even going uphill in AZ when its 120 ambient.
And I run this
It only incrementally cools on the highway when the air blows through it.
But it works.
With this puppy, always under 180.
Cooling Pans : GM 700R4, 4L60 & 4L60E Transmission Cooling Pan (derale.com)
The AZ desert can kill your transmission....sometimes it hits 125-127.....
Its hard to stand outside in that.