So what are the symptoms of a popped valve seat on an air cooled engine?

For those of you that have both an oil temp gauge and an cylinder head
temp (CHT) gauge installed on an air cooled motor; do the temperatures
track eachother closely?  Some argue that the oil temp should be kept
below 225, if my oil temp gauge never exceeds this limit does that pretty
much guarntee that the cylinder head never exceeds, say 400.  Or can the
CHT be too high while the oil remains at an acceptable temp, or vice versa
for that matter?

jake
82 AC Westy