is the z24 front bumper different longer/wider then the regular cavalier front bumper   [non z24]
 
no, different yes, and no 
will it fit ? yes..   any modifications for it to fit?  a bit. 
 
 
Its been a while since I had a Z24 front but I think all u gotta do is trim the honeycomb a bit, either way it should be pretty straightforward once u put it on.  
 
 
ok cause i got a sunfire a i was thinking about switching to a z24 front
 
are you swapping your sunfire front for a cavalier front?
 
i put a z24 front on my vert and didn't have to modify anything i may have gotten lucky though  i also swapped the rear as well that  took a little trimming. to fit right.
 
 
I have a 2000 Cavy and I went from a base (non Z24) front bumper to a Z24 front bumper and all I did was take the old one off and put the new one on.  I didn't have to mod anything.
 
did u have a sunfire and swithched it over