Paul,
This is an engine that was prepared several years ago for gyrocopter
use.   Do you recognize the style of  the workmanship well enough to
guess who may have built it?  I has an IVO prop hub and the large
friction wheel for the rotor drive assist.  A welded fitting on the top
of the water pump has been broken off.  The PSRU  has a 2.85:1 ratio.  I
have not seen  a Ross unit  with the conical shaped bellhousing.  Does
that indicate it is an early Ross?  I haven't taken any of it apart yet,
but looking through the exhaust ports, the rotors and housings look
nearly unused.  I has 2mm metal apex seals.  It came with a nice light
weight starter which I am trying to source (it is similar to the Mistral
starter).  What is your opinion?

Aubrey

You got me there. No idea. I kind of like the oil pan however.

You will have to take the Ross off there and add a thrust bearing.
We have details for doing that.