I would not waste too much time wondering. Now that you have the intake off,
just pull the heads and either check them yourself for cracks or warpage, or
bring them to an automotive machine shop. To properly check them for cracks,
they should be disassembled so the valve seats and valve guides can be
checked. You might as well have them freshened up. Generally speaking, heat
will damage the heads before the block or pistons. If you want to try and
spot the damage yourself, look carefully at the areas around the exhaust
valves, particularly the middle two which are adjacent to one another.

--
Ron White
My boatbuilding website is:
www.concentric.net/~knotreel