Back in 2009 there were some pictures posted about these mills but they have all gone now.
If you do a search for spearer you will see there are a couple of threads about them but with no pics they are a bit meaningless.
The SPerbers I have seen were all designed for twin power head use - i.e. no handles in the middle section of the mill but I believe there were some that were made for single powerhead use.
There was a member here called railomatic that resurrected some of their design aspects in the mills he made but not much of these have been taken up by CSM builders
Quality and engineering is impressive. I need to dig it out, you're right on the bar it's a double ender bar that takes to 084/088 stihl powerheads. Serious setup. Mine came with the "suicide" handle so I can run just one powerhead. I'll have to pot some pics