Smitty
You're in trouble. The length of the fuel line is not the big issue. It's the position of the tank with respect to the carb. You have made the effort to get it right with the plane level. Now point the nose up and see how far below the carb the tank is. It's much further below than if the tank were right behind the firewall. This is going to cause a problem that generally can only be solved with a high pressure fuel system and regulator i.e YS engine or Cline regulator.