Check that there isn't a shimmy in the front end at speed.. that means
new lower control arims in the front end (which you've probably done to
your 94..)

Other than that - the I6 E39 is pretty much bulletproof. Price is OK,
but you might try for $12.5 and see what happens.

Try looking up the following website and checking the buyer's check
list.

Also keep in mind most of the comments there applied to the 528 and 540
models.  I think the 525 model is likely to be more robust because the
rest of the car is probably over-spec'd for the 2.5L engine.  The 2.5L
engine is otherwise a wonderful powerplant.  It all depends on how you
intend to drive the car.

http://www.bmwtips.com