Airone Sport 1951 seat size

Hi Folks, I have already posted this in general banter but thought i would stand a better chance on here.

I need a seat for the Airone as it came with a dual seat which had never been fitted. the bike was a basket case. I can buy pattern ones from Italy but would like to try alternatives. All I need is the overall dimensions e.g. length and width of an original seat.

Many thanks for any help.

Regards Barry