Hi Greg,

Reversing the engine is a relatively straightforward task.
Simply mode the Hall sensor to to the other side of TDC, an equal distance as the distance you currently have, taking into account the width of the sensor itself
(The ignition triggers when the magnet passes the trailing edge of the sensor)
You can get cheap calipers to verify the timing in degrees before you drill the front housing and permanently mount the sensor in the new location.

Menz (from memory) have a good range of pusher props.

I am doing pretty much the same thing with a pair of G62-Lite from Ralph Cunningham. I'm mounting those into a 27% Cessna 421 and am planning counter rotating props as well