Tailcone - I am just gonna claim victory

After much stress I did figure out the problem.  It was completely in the "keeper rivets" that hold 712 to the rear of the tail spring.   These should be drilled in assembly so that you can be sure 712 is plumb with 711.   Just using the bottom skin does not ensure this "plumbness" so when in full assembly with side fuse skins if the keeper rivets are in place it will skew the tail in weird directions..  

So to solve my problem, I had a tough decision.  Removing the tail spring is impossible without drilling out several tough rivets on the bottom skin, which in turn requires taking apart the entire structure one more time, and ends up impacting many other componets.   So to avoid doing this I took the simple approach to center the offset holes between 712 and the tail spring while in assembly and plumb, then open them up to 1/8th for larger rivets.   Now how to deal with shims and dimpling of 712 without taking out the tail spring?  Well my dimples are somewhat still there from the smaller rivets but now have lined up and plumb holes.  I countersunk the rear of 712 slightly to allow for the bigger rivet.  This is no problem because there are two ribs together and the countersink will only impact the first rib.   So Viola !    All lined up with the larger "flush" rivets that won't have any impact on future clearances.  :-)  Flipped it upside down, now we should now be good to go for riveting.