K5 is a hell of a start right out of the box.
www.ck5.com if your haven't found it yet.
www.offroaddesign.com is your friend. Give Stephen a call for your needs. Tell him I sent you.
First thing you need to get is his steering brace. The frames are prone to cracking around the box. Second thing to get is the sway bar disconnects.
How old is the fuel pump? I have seen more pumps fail then anything else. What happens is if you run the truck with only a few gallons of fuel in it all the time it runs the pump hot. Try to keep a 1/2 tank in it at all times.
The other problem is wit the age of the truck is it has a lot of sediment in the tank. When you start bouncing it around some of it will break up and it will get sucked up in the pump or clog the sock on the pump.
Bottom line is get a spare pump. If you go to J C Whitney or the junk yard you can get a 12x12 inch piece of the cargo floor. Cut a hole in the floor above the fuel tank to make an access hatch so that when that pump gives it up you don't have to remove the tank to fix it.
33's will fit the truck with no lift. However I would recommend a 2 inch front spring with a 4 inch raised steering arm or crossover and 4 inch rear spring to improve wheel travel and ride. Again ORD.
ORD sells what they call a Zero Rate add a Leaf. What it does is allow you to move the axle forward. With those wheels I would recommend to either get that for the front or re drill the spring perches and move the front axle forward 1 inch.
With those mods you will have a VERY capable truck.
A couple other things I would recommend is learning everything you can about the FI on that truck. Its pretty dependable but if it gives you a problem you want to know what to do. The vacuum lines are going to be very brittle...REPLACE THEM ALL! including the large hose going to the MAP sensor next to the distributor. Vacuum leaks play hell with that FI and is the #1 cause of most complaints. Usual symptom is a Serge at steady cruise. Keep an eye on the throttle body gasket.....its prone to failure.
Cross over steering is a great Mod if you can swing it. The drag link in stock form is very short and if you get driver side front extended it will bind the suspension and not let you turn.
Here is a picture of my last K5 with the Lovely Mrs Reaper at the helm.