Little late, but yes, I own one of these. 50cc with a 5-speed gearbox. 18" wheels. Extremely simple electrics. 40mm bore and 38 or 39mm stroke, I'd have to go look. Stock carb is an SHA 14.12. I have a Zundapp intake on mine with a 19mm PHBG. Exhaust manifold diameter is 32mm so there are a number of slip on chambers if you dont fancy having one made. I have a Homoet on mine. 28mm Marzocchi forks up front and Sebac shocks in the rear, adjustable for preload only.
These bikes shared engines with the Benelli Magnum and shared most of the running gear with the early 70's Benelli 90 and 125 monocilindrico 2t bikes. Some were also badged as Motobis.
Most (but not all) parts can be purchased from Detlef of benelliparts.de