sodium silicate block/head/headgasket sealer, does it work? risks vs benefits? (long)

[Mike Posner]

My 82 coupe which just got a new head gasket , along with an expensive
head rebuild  just  relapsed back int its  blowing the  overflow pressure
valve before the hot water (superheated) in the head had a chance to fully
circulate through the radiator.  I'm not seeing any h20 residue on the plugs,
compression is 150 tto 165 on all five, I  am seeing the same symptoms I had
prior to pulling the head.  I suspect the head is warped this time  as  it
over heated
badly  while my son was driving it home from work.  It didn't seize and
starts and
idles well, no smoking and  no h2o in oil or signigifigant moisture coming
out exhaust.
Plugs look oil free.   Tried to bleed air from head by backing out temp
sensors.  Also
shimmed the air intake thermostat as it looked like it was stuck on the hot
side
pulling in superheated air fror the em. Thermostat, h20 pump are new.timing
needs checking, but runs strong  so not likely off too much.

So before I pull the head off again to see  for warpage or damage to gasket.
I am toying with  trying a can of sosium silicate block sealer
that was suggested by a Napa  guy who claims it fixed a head gasket problem
on his  Mercedes.   Any thoughts on on this ?      TIA  Mike.