Aftermarket wheels on a '69 coupe?

[King Big Ben]

I originally thought big wheels on muscle cars didn't look right untill I saw a few with 17' American Racing Torq Thrust II's...so I'm considering a set of them on my '69 coupe but I'm not sure what i can fit inside the wheel wells without major alterations. First off will they fit in my wheel wells? I bought this car the way it was and it's lower than a stock '69...heard someone say i had a Shelby drop on it but I'm not really sure. Also, how wide can i go without sticking out of my wheel wells? I would like to try for the 17x11's in the back but it looks like it would take alot of heavy suspension modifications and such so that they wont stick out. It has Keystone Raider/Klassic's on it now that are old and rusted and the chrome is actually starting to wear off...plus the center caps are beyond repair.
Oh and how can you tell what kind of rear end you've got? So much of this car has been customized that theres no telling if it's original or not. Got my fingers crossed that its a 9' tho