It's may have already been posted somewhere but the s rom seems to use
void kf2k1spr_sx_decrypt( void )
{
UINT8 *rom = memory_region( REGION_GFX1 );
int rom_size = memory_region_length( REGION_GFX1 );
for( int i = 0; i < rom_size; i++ ){
rom[ i ] = BITSWAP8( rom [ i ], 7, 6, 0, 4, 3, 2, 1, 5 );
}
}