One small click on eBay, some years ago, and I had bought a 1992 245. Just 1 state away. Easy, eh? Towed it home.

Long story short, and my advice: CRAWL under this car, with a bright flashlight, on some nice cardboard (or similar), and take your time!

If it is rust-free, continue your evaluation and consideration of the car.

If it has rust, middling or more, say "no, thanks" and walk away.
(Search Brickboard for 240 rust locations, incl. rocker panels, floors...)

You WILL spend hours on the car. Days, if you are a normal human being.
Is it worth it? (Experienced hands on this site do things faster, better, easier than normal human beings -- take into account.)

On my buy, which was said not to run (true), the crank position sensor was suspect, so I replaced it. And the main relay always suspect, so replaced it. And this, and that, and the other... while I was at it. Covering the bases. Establishing a baseline. And would not run, until I replaced the 561 ECU. Hours of bending over, contorting...

When the oil pressure warning light went on, I had then had TOO much, and set it aside. For a TOO LONG time. Like your situation.

Then our family needed a car. The ONE THING that kept me going on this 1992 245 was its extraordinary (Florida) condition. And now it is a gem, with WAY too many hours in it. (what is your time worth? Do you have the time? Will you pay someone else?)

More experienced people will respond to your post.
And you can search Brickboard for lots of old messages on "sitting" or "storage" or whatever.

Advice:
1. RUST and RECORDS. Rust shoots the equation all to hell, badly; while maintenance records (especially using high-quality parts) enhances everything.

2. Your mechanic said what MIGHT or could or may be issues.

3. Try starting the car. If it runs. Drive it some, and don't worry about the fuel pump, fuel filter, fuel injectors, whatever.

4. BUT if it runs, bleed the brakes NOW (getting new fluid in them), and while each corner is up, you will examine rust on calipers, pad thickness, etc, etc. so as not to be an unsafe idiot to self and OTHERS. :-)