'91 carat, 220K, OE

had to replace right side head twice, went first at around 50K, next around
150K, give or take 20K on the second replacement (without consulting repair
records).  first one included new valves, second was done on the cheap
swapping old valves onto new head.

original left side head finally went around 190K, right side still cooking.
compression ranged 125-130 when last checked at 205K.  didn't ask by
cylinder #'s....that was dumb.  but then the shop showed no alarm over the
#'s.  engine runs great.  recent coolant flush and pressure test with no
leaks after replacing one of the front clamps.  oil/filter changes done
faithfully every 4K over total 220K.

got back into DIY mechanic-ing only within last year and cannot comment on
what brand heads were used.  no apparent ill effects noticed by not swapping
out two at a time.  one man's experience.

best, pete