Okay ... it appears that the group wants to move away from the Atkinson engine.
I do agree with difficulty factor, as I have said ... we could overcome those issues.
Having said that, there is one issue that does makes the MK3 not a good team build ... cost. Brian Rupnow on a similar engine spent over $150 just for the bearings, about $60 for the belt and sprockets. Other material cost and mailing could be rather expensive. Image making 8 bases and shipping them out. I'm sure some costs could be equally divided between members ... but could be major issue to overcome.
So let's move on ...
Elmer #29 looks good ...
Walking Beam .... can we get a specific model?
Other engines that were mentioned ... can we get a specific model?
With a model we can look it over and decided which one to take on...
Now who is still interested in this team build and what do you suggest (please be specific)?