Engine mods while she's in the shop?

Hi folks, I lurk around here a lot but haven't posted for advice before. My XJ is a 99% stock 4.0L 1998 (as the name suggests) with just over 200k miles on her. She's had a slow oil leak since I picked her up at 135k, but it's finally developed to where she marks her parking spots every night. I'm looking hard at sending her in to have all the seals around the engine freshened up. I'm military so I don't have a lot of time right now to devote to thorny problems like the oil pan gasket but I'm a believer in preventative maintenance.

To get around to my real question, I have a budget of $1000, give or take a little. If I'm getting the engine pulled to have the gaskets and timing chain redone, what else could I have done on a budget while the engine's out? The only performance mods I have are a Trail Jammer kit and a high-flow cat and muffler. I've been tossing around the idea of a new camshaft, but maybe I'm missing something obvious. Any suggestions from the community?

The engine doesn't need to be pulled to repair any of the oil leaks or change the timing gears and chain.
The rear main seal, valve cover and the oil filter can all done with the engine in place. If you are having it done at a shop, it's going to use a fair chunk of your $1000. Do you have other reason why the engine needs to be removed?
Upgrading to a bigger radiator or a cat-back exhaust might be good ideas if you have extra cash.

I'd just fix the rear main seal and leave it alone....you should get 40 to 80 thousand more miles out of it before it gives up the ghost assuming it has had a normal life.

When it does go, just rebuild it completely

Since you say you've already got an intake and cat high flow exhaust. I'd put a 2in spacer lift on it. Bump stop the drivers side to keep the axle pinion out of the down pipe, and replace the crushed portion with a full portion. I'd then have the throttle body bored, and throw a set of mustang injectors in it.