o.k.

Anybody seen a SIDEVALVE around 8 to 15 cc that might be adaptable to control line ?

Maybe the power characteristics could be usefull , they wernt entirely hopeless .

Thanks , this just popped up , http://www.modelenginemaker.com/index.php?topic=3573.0 , and theres a old pommy inline twin , marine. kit available
http://www.modelenginenews.org/etw/seagull/index.html

But there must be a weedeater or some resonably light comercial thing about , everything used to be ' sideys ' once . Maybe its all two stroke or o.h.v. these days .

Thinking the ' shortness ' , same as a two stroke - with the valves adjacent the cylinder , means a big square finned thing would cowl easy .
And hopeing the ' flat power band ' would be applicable , for F2B . 

And theres these ' drone ' engines, https://www.d-motor.eu/ . but 125 Hp might be a bit to much .