Hey unc Man u have been busy !! All the repairs look great. If its eating coolant and you cant see if its external then I would have to say your HG is leaking into #4 via the coolant port between 3 and 4. Mine leaked like that for well 6 months before it finally got bad enough to force me to change the hg.
If you can post pics of plugs 3 and 4 close ups. Plus have you done a compression check yet ? Heck a leak down would be even better.