Problem with 180sx rotors and pads

[Fastback240]

when I did my srswap I got a 180sx front clip. On it the brakes and rotors are bigger. Recently my front passenger rotor cracked so I replaced it with a stock replacement rotor for a 93 240 and the pad doesn't completey fill up the rotor. I need to know what size the rotors are for a stock 180sx and where I could get them. It was also be nice to know where I would be able to replace my pads at.