i mean is the Pins configuration is the same or not.
Once more: I can't till you tell me which package.

A guess ( verify with the datasheets) is that you can use the P89C51Rx2 (x= B, C or D depending on internal flash size) Using one of those you will gain ISP as well.

One word of warning: when replacing like derivatives you will sometimes find that SFRs with identical names have differenty addresses, verify the SFR address list in your assembler/compiler with the one in the datsheet.

Erik