Intake gaskets wicking coolant

[1] Have you checked the manifold against the heads without gaskets in place? Gaps because of poor machining?
[2] Could the manifold be touching the china wall such that the gaskets have a gap?
[3] This works, been doing it for years, do it every engine I build, for a better seal. Get a Dremel with a 1/10 - 1/8" carbide rotary burr. [ Get them at Bunnings ]. Grind a depression around the coolant openings, on the heads & the intake man. Go about 0.020-0.030" deep. What this does is create a trench or anchor. Use silicon to seal it. The silicon does not get squeezed out because it is locked in place. I have even used the cheap Parfix silicon from Bunnings, no leaks.