Just put a Ford starter solenoid in the back near the battery. Use it to switch the power to the starter that way the long wire forward to the starter is only hot when you need it hot and dead all the rest of the time. You will need to run a separate, fused at the battery feed for the fuse box.
That is the first step and often required by some racing bodies but once you hit crank it's full power to the starter. In my case the starter had worked loose and the main positive wire was grounded at the starter. Hit the key to crank and poof. Big smoke. No real damage. Had the main line been the same as the ground I would have probably lost the car since the power wire was run inside the car along the rocker the same way the factory does it now.
Back to the original question. Some people have mentioned that they have used that tab. I like a little more metal myself. Like I said I ran my ground to the trunk latch bolt but a direct bolt into the frame (like others suggested) would probably been better than my way. I did my way so that if I moved the battery back to under the hood it would be a simple unbolt, but truthfully so would a bolt to the frame.
Also a switch to a modern starter would reduce the load to the main wire. Modern gear reduction starters use less amps than our old Chrysler gear reduction or the GM/Ford direct drive starter. Just look at the size of the battery cables on modern cars compared to the old ones.
