Welcome back, and it's great to hear that your health is improving! We're glad to see you around again.
Regarding the Vanguard 613477-3048-G1 issue, it sounds like you've covered a fair amount of troubleshooting already. If the engine runs fine when gravity-fed from a test tank but there's no fuel pumping to the carb, it could be a challenge with the fuel pump or the connection to the intake.
Since you've tried multiple pumps, it might be worth double-checking the connections and ensuring there are no blockages in the fuel line. If the hose from the engine to the pump is fine, you might want to inspect the connection points for any potential issues.
Considering the engine ran for a few hours with the existing setup, there might be a specific point where the fuel delivery is being interrupted. If all else fails, installing an electric pump could be a viable option.
Feel free to keep us updated on your progress, and the community is here to offer further assistance. Wishing you smooth troubleshooting and successful resolution!