There is not much room on the inside, I have rims with a 4 1/2 inch backspace on my car right now and only have about 3/8's inch clearance on the drivers side. If you move the shocks inboard you will gain some more clearance and it is supposed to make the car launch better, I will probably do this to mine, time and money permitting. I have a 68 Camaro so I am limited to how far out my rims can go. I refuse to have a car with any gap between the top of the tire and the fender opening (I want the fender to sit over the top of the tire). Your 69 has a much larger outer wheelwell, because of the coke bottle design, this is where you will get extra tire clearance. I assume that is what you are looking for. I have seen several 69's with L60's in the rear, I think they got them to fit by rolling the outer wheelwell lip and using a sledge hammer on the inside. If this is not what you want post what you are looking to do.