A spare battery & jumper cables might get you an answer here. If it turns over and the timing chain is running smoothly through the guides, the belts are all turning, etc., you know a lot more about the car than you do now. How does the oil look? Transmission fluid clean and up to level?
IMHO, any $1K is very well spent for a parts car when there is something on the parts car that you can use (or really just want) and the item's real current value approaches 1/2 the total price paid: i.e., if you need a windshield & back glass for an S-Class, better leather seats, a dash, engine, transmission, suspension or electrical parts, etc.
AND
you have a viable place to store the rest of the car.
Not everyone has this luxury. I just acquired a 2nd W126, an '88 420SEL with 171K that has too much value to me as a daily driver to be relegated to the term "parts car", although that's what I bought it to be.
Now I need to find another W126 to be a parts car FOR my "parts car".
Cheers!