1951 Series 62 Convertible knowledge request

[PATROCKY]

I am bringing a 1951 Series 62 Convertible back to life, for a family friend, Whose Father passed. I am requesting any knowledge I can get. Her Father did a few modifications to this vehice. I Absolutely respect factory perfect restorations (I am a Degreed Mechanic (retired after a few decades) (Formerly certified ASE Master Automotive Technician).

Every place online I ask for help, I am only offered info on how to correct Her Dad's modifications (mistakes)back to factory. This was his Unicorn Vehicle, that he gave to his Daughter, to be driven, she is not looking for correct, she wants to drive this beautiful vehicle, not sell it

Engine Casting 1460088


Late 1960s Dad swapped single carb for 1955 Eldorado Rochester 4G Dual quads. Carb tags
7007240 & 7007241 manifold stamp also matches Carburetors.

i am seeking the baseline tuning procedure for this dual qual set up, all knowledge is appreciated on this topic.

ignition timing, I understand that fuel was dramatically different in 1951, does the A and C marks still work with 2021 premium gas?  As I am finding the timing a bit retarded when set to either mark.

Was an  fuel line check valve needed on this Vehicle? Fuel is being siphoned back to the tank overnight, not leaked into the intake, aftermarket Carter electric fuel pump installed.

Last I am finding conflicting data on the Hydrolectric  fluid  capacity? I understand 51 was a transition year (correct me if I am wrong)  pump in left fender has 1 pressure outlet with junctions behind kick panels to power door glass, a 6 outlet panel under rearseat rear window and convertable top pressure and return lines, the hydro seat, plus windshield wipers? Some sources quote 42 oz, but looking at the top pistons, this is not enough fluid. Also can the system be vacuum bled from the under hood (return pump?) With the bleedet valve at top of firewall mounted unit?

i really value any help. Thank you