The fuel system mods are complete.
For the fuel return line, a 3/8" SS tube was silver soldered into the "S" bend fill pipe and a -6 fitting silver soldered on the end so a -6 SS braid hose could connect up with the return line.
For the fuel tank venting, a hole was drilled into the LeMans cap base and tapped for 1/4" NPT threads. A series of fittings and a tip-over valve were installed and these connect to the fuel tank vent pipe with a 1/2" hose.
Once all the bits were re-installed, the small black hole under the flip cap and the three extra holes in the top are the only external visible parts of the modifications. I did run a ground wire as Morris suggested from the LeMans fuel cap to the battery ground to help avoid static electrical discharges where fuel vapors may be present.
So for about $150 in fittings and hoses, the fuel tank should now be properly vented and fuel returned to the tank. I'm going to monitor for the smell of excessive fuel vapors and if so, will look further into the fuel pressure regulator setup. Thanks for all the input and information from those who've commented on this thread. The end results came out very clean thanks to Morris's suggestions.
Now for some spirited test drives to make sure the fuel tank pressurization issue has been fully resolved
