From Z3M setup the top mounts are the only compatible parts (along with the "reinforcement plates").
I think I forgot to mention that I had to cut and grind part of the spring top plate following Jon's advice on his site. This is necessary as the Z3 top plate has a kind of lip that protudes and would hit the inner arch such is the difference in castor when using Z3M top mounts. Even when this is done the struts do sit close to the back inner arches.
Using lowering springs on my standard 2.8 there was an very obvisouy increase in negative camber; I'm not sure how much camber is acceptable according BMW but it was a lot more than standard (not sure what a Z3M has but they're not as low as my Z3 is now). So fitting the Z3M mounts the correct way resulted in reduced negative camber but still some neg left.
If you camber is said to be fine then you will alter it fitting Z3M top mounts; fitted t he "right" way you will reduced negative camber, and the wrong way you will introduce a lot more negative camber. You might be better off fitting 1995 M3 top mounts as these appear to just add castor rather than altering the camber either way.
If you look at this very useful site http://www.realoem.com/bmw/select.do?vin=&kind=P&series=Z3&body=roa&model=Z3+2.8&zone=ECE&prod=19991100&motor=M52&steering=R&arch=0
it lets you view all BMW parts and part nos. alogn with a USD price for a rough guide to the cost of parts. Just select E36 M3 1995 and search for front axle strut assembly parts.