Compressing overhead

I did a live recording. Only 9 tracks. The drums were on 4 (two kicks,
a snare, and an overhead). Went back and redid the lead vocals. The
only remnants of the old vocals are on the overhead track, but at a
fairly low volume that can't be heard with the new track in place.
The overhead caught the toms and cymbals pretty well. However, as I
said, it's got the old vocals on there as well. How would I best
compress this in order to bring the cymbals and toms out as much as
possible without bringing the old vocals up? What would be good attack/
ratio/threshold/release settings to start at? I assume I shouldn't put
too much on it. Any other things I can do to bring these instruments
out?