The 98 (as far as i know) only the 523, and 528i models were available in 6cyl, maybe a 520i. Anyway, the E39 has a larger hub diameter than the E34 wheels, so you will need a set of hub-centric rings to take up the slack, otherwise you will have a nasty vibration. If you can locate a set of them, possibly from www.tirerack.com, you should have no problem fitting them. The E32 7 series 88-94, E31 8 series 91-97, and all E34 wheels will fit no problem. I'm sure there are a few more, that's just off the top of my head.
1995 540iA M-Sport - 76k miles. 1 of 1 auto AW3 cars.
1995 540i/6 - Misc Parts donor for above.