Now I have the spacer sitting right I can take some still rough but better measurements for port timing. I cut some .8mm paper gaskets for either side of the spacer and installed it all on another motor. At TDC the top of the outside of the Piston sits and 3mm from the start (outside) of the squish (the squish is a separate insert in the head and sits inside the bore by 2mm). Then at BDC the Piston sits 1mm below all the ports. The spacer was made thick so I could face it as needed.