Even if it would really fit with a few adjustments, then still, the power range and characteristic of the speakers is to different. In power alone I think it is a factor 1:4 (25 to 100 Watts) Beolab 8000 wil also sound very different based on yield and one time the volume level too high at the Beolab 8000  and the Beolab 2000 speaker also runs out the coil, that the scratching more worst is then the old one. Fitting is a matter of measuring or try on error, but the technical specs are  to different.

Thanks Leon, thats All I need.