Will also solve the filing up process, because with just a T the tank will slowly drain as you fill it up.
I agree.
Even though it’s a complicated system, and gave me a lot of grief until I sorted it out, it’s a unique feature of these cars and has it’s advantages.
Mind you, the change over valve is not that great design and might cross leak even when new.
If you are going to reinstate the system from scratch there are alternatives.
One is a Pollak fuel valve and you get away with just one valve as it handles also the returns.
Another is a three port motorized valve and you keep the original return valves, or you change them as well with two port valves. Keep in mind that the Right is NO and the Left NC.