I may not have the diagram for that particular motor Cameron, but you probably do. The one below will be similar probably. The earth connection can be seen on #49. Also, however, do check the fuse that is on the constant power supply to your EEC. When mine had been sitting for some time that fuse became corroded (some road water had managed to get in earlier) and was the cause of non-starting problems. Took me about 12 hrs to find that! I also used the starter fluid down the intake - it would run then stop and so on. I suspected every single component and wire! It was a simple power supply and a poor earth. I am thinking that yours will be the same.
There also is a whole heap of info on this site which may help. I have some pics as well if needed. Good luck!