yeah the report here
http://mametesters.org/view.php?id=3948
gives details of it.
At least 2 bytes are bad. It's possible if his roms were suffering from bitrot that he won't be able to get a good read from that board anyway, but it's worth another try. The CPS2 ROM checks are useless, they check almost nothing so don't really detect such problems well.
It's almost definitely at least 3 bytes. Two of them are in the word at 80040 and the other is in the word at 80060.
The proper decrypted opcode value is the one in the middle column, the right one is the bad value.
80040: F9 11
80041: 4E EB
80060: 7C 43
80061: 22 08
Running the cps2 decryption algo and brute forcing the value to give the proper decrypted value at the bad addresses gives these as the most likely "good/encrypted" values:
9A18, 80040 <-- most likely (3 bits difference)
0A7E, 80040
5780, 80060
0BC0, 80060 <-- almost definitely correct for this address (only 1 bit different)