Isotta-Fraschini Asso / S.65 engine info

Hi all,
Anyone out there point me in the direction of any decent photos / drawings of the Isotta-Fraschini Asso engine, in particular the variant fitted to the Savoia-Marchetti S.65.

The S.65 being the rather radical Italian push-pull Schneider Trophy contender in the 1929 event. The Asso engine a big old V.12, unusally with the exhaust ports on the inside of the cylinder blocks, these blowing out of the top of the cowlings, or so it would seem?

I have books such as the Putnam Schneider volume, Smith and Moldon soft covers etc, any other source of info greatly appreciated.

Cheers, Chumpy.