Actually you will be doing yourself a favor when you move the 5.12 gears out of your manual into your automatic.
Because of the extra low-range out of the auto tranny, a stock auto tracker comes with 4.62 gears.
Putting your manual differential gears in the truck will help a LOT!
You might see a small difference with 33's as I believe 31's or 32's is where the truck would feel stock again. 33's are a little larger, so, your truck would be a little slower than stock.
Make sense?
(I hope?)
Oh as for the second part of your post, Yes, with a little modification to the springs and the spacers.
Heather