Yeah, we all know how GFR was, but don't you think FFC would make a better extension of the sage then Mark WG.
Like I've already said in the GF IV board, the main characters would be.
Young Vito Andolini, Pietro Clemenza, Salvatore Tessio, Genco Abbandando, Tommasino.

And Antonio Andolini, the fathers of Clemenza, Tessio, Genco, and Tommasino.

Also starring: Paolo Andolini, wife of Antonio Andolini, and maybe Vito had a sister. And Don Ciccio should be in to. Or perhaps family members of Cuneo, Barzini, ...

Storyline could be that the father of Antonio Andolini was a local (great) Don, but he had problems with an agressive Don Ciccio. When the father of Antonio died, Don Ciccio wanted to take over the power, but Antonio wanted do steo in his fathers shoes too, for which he had been murdered.