Uh oh. "A "bit" hot? Not good.

Like what kinda "hot"? The gauge needle was rising when he shut it off? The
gauge needle got into the red? Like he saw steam coming out from under the
hood? Like it was clanking loudly and ground itself to a halt?

Big differences here.

Sort of. A pressure test (not a compression test!) will tell if the head
gasket seal has been damaged. Unfortunately that's only true if the seal
has already failed. If it's been compromised but is still holding, nobody
can tell until it finally blows its top.

It's not the head you need to worry about. Straightening or skimming that
is only about $60 once it's off the car. If the *block face* is warped or
corroded, the engine is scrap, economically speaking. Severe overheating
will often scrap an engine.

you can do a coolant pressure test to see if the head gasket is leaking.
 or you can put in the new radiator and see what happens.  if the
gasket is gone, look into the economics of replacing the motor vs.
having the head and gasket done - it's a lot of hours and prep.  quicker
to replace the motor, and the motor only costs a few hundred bucks jdm
import.  do the math from there.  google this group for head gasket
replacement stories and figure out if that's what you want to pay for.
[personally, unless i had a rare motor, i wouldn't bother rebuilding
again - i'd just replace the whole thing.]