Here's a II with an external engine:
http://www.dakota.net/~mik/album17.html
More pics from the source; this one has metal baffles over the cylinders.
http://www.warnerair.com/pictures.html
This one also has external engine
http://www.spacewalker.org/Pyle2.jpg
This page has pics of one with a fully cowled engine
http://www.spacewalker.org/index.php...wgall&gid=1&p=
The GP cowl may be accurate (except it isn't "lifted" on the sides) but there are other accurate ways to build the cowl.