The '502' is one of the few Konami custom ICs I didn't yet reproduced.So far I have succesfully done and tested the '501' and 503'.Lately I've also done the '082', '083' and '504' and I'm waiting for the boards from manufacturer.
I have a bootleg of Time Pilot with a '502' replacement board, anyway I think design is not complete and will not work on other boards.The '502' can be found on few PCBs, refer to this spreadsheet (credits to 'mattosborn' on KLOV forum)