Max Width Of Rear Wheel/tire

Im looking to put Cragar V5s on my 73 swinger and i wanna put as much meat on it as possible. Does anyone know the widest tire you can put in the rear wheel well? Also my dart has the stock sunroof option and parts for it are as rare as finding gold! Anyone know a place to find parta for that? Im brand new to this forum and look forward to chatting with all of you!

Thanks in advance for any feedback!