If you plan to lift, you'll be putting bigger tires on? If you don't like the power response now, bigger tires are gonna make it worse. Look into 3.4 swap.
Btw, if the fluild is dark, you might wanna bleed the brakes till it clears up while adding new fluid so there's no air in the lines.
You can take it to any shop to do it if you're not up to it.
I got a 5 spd and the door info matched my gear ratios which was 4.56.
I went to 5.29 when I moved up to 35's after SAS. I plan to go back down to 4.88 since I've swapped the 3.4 engine. 3000rpm at 65 mph is not ideal.
If you plan to run it on the trail, you need to get rid of the running board first.....or just wait till the trail eat it up.
Ride along with a local club first. It should give you a good idea of what you're getting yourself into. Your truck won't look like that for long if you're hooked.