Hi Parv,
To create a query, you can do a join with BSIS, BSAS and FAGLFLEXT (if you're using New-GL). There you've amounts posted in the periods, with cost center and other fileds. Check these tables fileds in the SE11 and fill with a table above.
Also, you can try use FAGLL03 tcode to display line items or FAGLB03 to display the balance filling cost center. Rebember to fill all parameters.
I guess you've many options before to create a Z report.
JPA