I built up the complete assembly according to the instructions at wiki.MakerBot. Then I started to brain storm ways of attaching it. In the end, there was only one practical way of mounting it. Here is the configuration I came up with:
Both the dinos had to be removed. They made the whole assembly as large as the Z sled. I set them free and they are able to rome around the shop and feed on future discarded prints.
I laid the plastruder assembly down on some graph paper to get the relative distance from the extruder nozzle to the mounting holes.
I wanted to create a template for an adapter plate that would hold the extruder board and the remaining of the plastruder assembly. So, I down loaded the Eagle files for the extruder board and exported the Dimension and the Holes layers as a dxf file. This gave me the hole pattern for both the extruder board and the plastruder since they bolt to one another using these. I then arranged these in my CAD software such that the nozzle was centered on the Z sled. From there it was easy to see that the inside mounting holes for the PTFE bearings would make good mounting holes for the adapter plate. The adapter plate was made out of 3/16" fiber board. It's what I had on hand.
After mounting the extruder board and the plastruder to the adapter board and on to the Z sled I saw that it needed to be lowered about a good 2". A quick run to the hardware store and I got some different lengths of pipe to adjust the Z sled height. I ended up swapping out the 12" piece with two 5" pieces and a coupler.
The Y alignment is not quite centered yet. Good enough for now though.
Over all I think it came out pretty good and will be easy to swap out print heads. I'm thinking of putting longer screws in from the other side and securing the board with some screw on knobs or wing nuts.