Filler neck through the trunk pan location

[gzig5]

I'm rebuilding my trunk pan on my 73 Cuda.  The back center section from the rear cross member forward about 10-12 inches was pretty much eaten up.  I'm using sheet steel because I will redo the whole thing including quarters as soon as time/space allows and I didn't want to waste $$$ on a repo panel just to cut it out again.  So, I've got the main part patched in and am reproducing the raised section the filler neck goes through.  It would be helpful to know how far from where the trunk pan meets the vertical tail panel, the oval hole for the filler neck starts on that sloped section.  The part that was left is too mangled and I forget to measure it before it was cut out.   I'll mock up the tank and filler neck, and then open the hole but I don't want to cut material where I don't have to.  Even a measurement from the tail/trunk junction to the back end of  the filler neck gasket would get me in the ball park.  Can anyone help?

[Chryco Psycho]

Someone should be able to measure this for you 

[gzig5]

Someone should be able to measure this for you 

I would think so......come on guys, I'd like to tackle this tonight.   

[Rich G.]

21-1/2 from the bottom lip before it goes up by the spare tire mount and 3-1/2 from the tail panel

[Rich G.]

Oh if you're talking about the truck latch mount. That cut out is 7-1/2 inch's fro the floor cutout