As the title says. I have cut out the rear quarter smaller than the replacement panel, and I am ready to start drilling out the spot welds. While looking at how the two parts of the inner fender and the body are spot welded together I am wondering if it might be easier to remove the whole rear fender to give access to the inner fenders? I have replaced on other cars many quarter panels, rockers, and such so this is just a question of access and advice. 

I will also be replacing floor pans, rockers, front quarters and under the battery tray. The car is down to a bare shell and has been media blasted.

Thanks for your insight. 

Well if you are comfortable removing/replacing quarters then that is the best way to tackle the inner wheel wells, it also gives you access to all the other rust you just know you going to find.  The unibodies on these cars are not as stiff as modern cars so it's always a good idea to limit how much sheet metal you remove at one time so there is no chance of sagging.