Pull the door sill plates off and you should see some holes approx 1/2" diameter with or without plastic plugs. See if they line up with the holes in the frame rails.
Don't know for sure if they are exactly the same on the different years, but I don't see why they wouldn't be either.

Any input on the spring issue?

In all honesty, Scott, I would be remiss if I gave you advice on a rear spring, when it appears you have a body alignment issue. My advice is to stop, step back, and take a couple of deep breaths....

This discussion started out with a discussion of tires being too big and hitting the fenders, but in truth they're two sizes smaller than GM eventually offered on C-3 Corvettes. There was also discussion of adjusting camber to gain tire clearance, but in reality, you adjust camber for proper handling and tire wear.

I truly believe the picture you posted, looking into the wheelwells, are the key to your problem. You have to figure what's keeping the body from sliding over. Sometimes, you can't rush a project car...

As it is now, the fender to tire clearance is equal on both sides. I was hoping a quick nudge would slide the frame over but thats just not going to happen. In all reality, I could only have shifted it over maybe 1/4 inch for perfect alignment. The bubba shim that i put between the frame rail and the frame pushed the well out a bit too. I think the camber may have been more at fault than the fender overhang. But my big question now is how far is this rear end supposed to normally compress? If I have tire scuffs at the top of my wheel well, then Im thinking a worn out spring combined with an out of camber tire was making too much contact with the fender.

Please take another look at my tire/dowel pic. Does anyone else have this kind of clearance and have no problems? (IE at what point of compression does everyones sidewall hit the fender?)

As the suspension compresses, the rear camber will go "negative", as the tire pivots around the lower suspension link. So the top of the tire will tip in more, therefore moving away (inward) from the fender. Therefore, with the camber set properly, you should actually gain clearance. Your picture shows plenty of room for compression and clearance, IMHO.

I've always thought that my rear suspension was too stiff. I'm lucky to get 2" of travel. My '76 has a 9 leaf, 2 1/2" spring, which supposedly a newer style standard spring. I use ac delco stock gas shocks.

Then it appears that my original camber adjustment may have been to blame. I may still replace the rear shock just because they arent that expensive. Everything with this car is a fiasco.

They should be fine...

What sort of measuring device are you using to set the rear camber?