Eero Saarinen for Knoll side chair series 71 or 72  

I have seen these chairs advertized as series 72 and series 71 I was wondering which they were.
Also does it make a difference if they have fiberglass backs or upholstered backs?
I have 4 chairs with the bent wood legs and 5 with metal legs the metal ones have an orange fiberglass back and the 4 with the wood legs have a black fiberglass back. I am taking to get them recovered but need to get a fabric does anyone have a suggestion for what fabric to use.
I was thinking of getting the orange fiberglass painted white and using the brown knoll fabric below on the seats and keeping the black one black and using the green knoll fabric below.
Do you think it is better to change things up with fabric or try and stay as close to the original as possible.