Out of frustration at not finding what I wanted, I took matters into my own hands. I welded in a 1" NPT fitting onto the fuel tank roof. Then took a 1" x 1/2" NPT reducer bushing and tapped another set of 1/2" NPT threads on the unthreaded end (these fittings are only tapped about half-way through as sold. Then I screwed two AN-8 fittings, one on each end of the reducer bushing so that one was pointed down into the fuel tank, and the other was point up for a fuel line connection. On the one pointed down, I attached a flared tube of proper depth. Now I ony need to screw the entire assembly into the 1" pipe fitting in the tank roof in order to install the pick-up tube. No gaskets, and no requirements to access the insides of the tank.
The left bushing is an un-modified reducer bushing with no internal threads cut on the non-hex end. The middle bushing is the same bushing only with new threads cut on the other end. The AN-8 fitting on the right is the fitting that will screwed into both ends (2 fittings) of the fully threaded reducer bushing
This shows the assembly with the tube sleeve attached:
And with the flared tube attached:
And lastly, the entire assembly is screwed into the 1" NPT hole. The hex tube sleeve slips right through the opening. The top part is ready to take any combination of fuel line/fitting. It appears that I'm needing to tap the 1" threads a little deeper in order to screw the reducer bushing further into the tank though.