I was talking about the leakdown tool I had to fabricate. I made a longer one and will do a write up in the DIY section. The leakdown test passed; no bubbles in the coolant. Also all cylinders were less than 10% drop.

After investigation I am certain my water loss is in the heater core. The wetness in the firewall insulation is only up to the level of the core and dry above that. Also I found signs of water hardening around one of the inlet pipes. I shunted the heater core for now until I can get it fixed.