I've got a similar sounding problem, and its not looking good so far, beginning to dispair.
Car (1.4 ZR) overheated last week, heater only blowing cold, thought I had noticed in time before doing damage, but now not sure. AA came out, said HGF. Fortunately, I know a few people that know K series pretty well, so was able to get new gasket fitted, head skimmed at a decent price.
Was no obvious signs of HGF though, water and oil had only just started to mix, so no mayo, head looked fine, but had it skimmed anyway.
However, the same symptoms still exist, overheats, loads of pressure in coolant system, and no flow of coolant.
Had thermostat changed, new water pump, still not fixed.
Had another gasket changed, this time with new head.
Still got the same symptoms again... arrggghhh.
I'm sure its been bled properly, stand proud heights of liners are all in tolerance (just).
Don't know what to do next.
Chap doing the job knows the k series inside out and he's running out of ideas. suspects problem with bottom end, but what???