Dirt Diver

I've owned 4 Wranglers. I have a 2003 Rubicon in the driveway now and this is my first XJ. I just bought a stock 2000 Sport model last week. The tires and suspension are in need of replacing. Other than that, I'm very happy with my purchase. That being said, I'm starting the upgrade process on it and I have a few questions...
1st, I'm adding a 4.5" Rough Country lift with new leaf springs.
2nd, I'm throwing on a set of 33x12.5R15 Mickey T's.

I believe it has a Dana 35 in the rear, auto 4.0 I6...Will it need to be regeared? Will the power lag and speedo be off? Overheat issues? Just want to know what I should prepare for so I can start looking into the solutions before they become problems. I got it up overhead on a lift to inspect it and the previous owner (a 20+yr mechanic) replaced a lot of the components, new brakes, starter, gas tank, lines, etc...It was incredibly clean inside and out.

Thanks in advance...