Maybe looking into MAME source???Too difficult, perhaps...
ROM_REGION( 0x600000, "gfx", 0 )
ROMX_LOAD( "sf2-5m.4a", 0x000000, 0x80000, CRC(22c9cc8e) SHA1(b9194fb337b30502c1c9501cd6c64ae4035544d4) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "2" socket
ROMX_LOAD( "sf2-7m.6a", 0x000002, 0x80000, CRC(57213be8) SHA1(3759b851ac0904ec79cbb67a2264d384b6f2f9f9) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "4" socket
ROMX_LOAD( "sf2-1m.3a", 0x000004, 0x80000, CRC(ba529b4f) SHA1(520840d727161cf09ca784919fa37bc9b54cc3ce) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "1" socket
ROMX_LOAD( "sf2-3m.5a", 0x000006, 0x80000, CRC(4b1b33a8) SHA1(2360cff890551f76775739e2d6563858bff80e41) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "3" socket
ROMX_LOAD( "sf2-6m.4c", 0x200000, 0x80000, CRC(2c7e2229) SHA1(357c2275af9133fd0bd6fbb1fa9ad5e0b490b3a2) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "11" socket
ROMX_LOAD( "sf2-8m.6c", 0x200002, 0x80000, CRC(b5548f17) SHA1(baa92b91cf616bc9e2a8a66adc777ffbf962a51b) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "13" socket
ROMX_LOAD( "sf2-2m.3c", 0x200004, 0x80000, CRC(14b84312) SHA1(2eea16673e60ba7a10bd4d8f6c217bb2441a5b0e) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "10" socket
ROMX_LOAD( "sf2-4m.5c", 0x200006, 0x80000, CRC(5e9cd89a) SHA1(f787aab98668d4c2c54fc4ba677c0cb808e4f31e) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "12" socket
ROMX_LOAD( "sf2-13m.4d", 0x400000, 0x80000, CRC(994bfa58) SHA1(5669b845f624b10e7be56bfc89b76592258ce48b) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "21" socket
ROMX_LOAD( "sf2-15m.6d", 0x400002, 0x80000, CRC(3e66ad9d) SHA1(9af9df0826988872662753e9717c48d46f2974b0) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "23" socket
ROMX_LOAD( "sf2-9m.3d", 0x400004, 0x80000, CRC(c1befaa8) SHA1(a6a7f4725e52678cbd8d557285c01cdccb2c2602) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "20" socket
ROMX_LOAD( "sf2-11m.5d", 0x400006, 0x80000, CRC(0627c831) SHA1(f9a92d614e8877d648449de2612fc8b43c85e4c2) , ROM_GROUPWORD | ROM_SKIP(6) ) // in "22" socket