First things first.
Make sure the car is in tip-top shape in every system.....like the tranny. Then think about your mods.
I'd leave the exhaust alone since it's already on there. $3000 can go quick. Get Mark D's chip for $179 or so. Make sure the brakes are in tip-top shape and the cooling system too. Check out the suspension as you may need thrust arms with new 750 bushings.
Next get the tint and tires/wheels. You have 15" wheels. Look for BMW....repeat...BMW wheels in 17". Ebay is a good spot but look through all the lists for sale stuff. As an example, BMW M5 turbines with tires sold for $666 a couple days ago in the LA area on eBay. That is one of the best E34 wheels with tires that would have lasted you a year.
By the time you have that done, you'll have your feet better on the ground. The most important thing is that the car be good for a "round" trip and be able to stop. A 525 is not a rocket but if you work at it you can set it up for world class handling and have a lot of fun. Just take it a little slower.
Mike Holbrook
Meridian, Idaho
1992 535im, 17", Euro M5 Throwing Stars 8's & 9's, FK-451 235/45s & 255/40s, M5 Sway Bars 25/20, Conforti chip, Lowes Ram Air, glass sunroof