Dear Franklin,
the best source regarding Capitano Bonet's last combat is "Centauri su Torino" a wonderful and accurate 250 pages work in Italian language with a short english summary written by Giancarlo Garello (among the best Italian air force history researchers) in 1998 and published by the authoritative Giorgio Apostolo Editore (ISBN 88-87261-04-0), the book is probably still available.
I must confess that I'm not very interested in details such as the individual numbers of the planes by I quickly look into this book to search for the data you asked only to find that apparently the only official info present is that during Capitano Bonet's last combat on 29 March 1944 the Fiat G55 MM 91061 and MM 91062 were lost. It is not specified which of the two was the plane of Bonet but the dustjacket of the book suggested that MM 91061 was the "yellow 5" and being the book almost dedicated to Bonet one is led to think that this was his plane. Regarding the "yellow 8" this machine was -according with Giorgio Apostolo and Giovanni Massimello's Osprey Italian Aces of W.W 2- the MM 91065 so it was not the plane of Bonet the day of his demise.
The combat career of Bonet started in Spain during the civil war but it seems that he drew first blood over Soviet Union in 1941 where he claimed only shared victories with 22° Gruppo CT (it was the habit of this Gruppo to assign only shared victories to its pilots in Russia). Then -during home defence- Bonet flew with 2° Gruppo CT and it seems that he claimed at least seven individual victories (eleven accordin with other sources). After September the 8th 1943 Bonet joyned the A.N.R. and claimed his final victory over a B17 during his last combat so his total was eight victories (or perhaps twelve) plus an unknown number of shares.
Don't know how to obtain a photo of Giovanni Bonet but you can try to ask Giorgio Apostolo
info@apostoloeditore.com or perhaps Great Italian researcher Ferdinando D'Amico -that is among the best experts of A.N.R. aviation and I suppose member of this forum (nickname veltro).
Hope this helped and thank you for your (quite rare) interest in Italian aviation.
Ludovico.