Apparently Earl said he only changes heads if he breaks one, so forty-five years isn't out of the question.
Guest, I'll watch for them to reply. When I first replaced the head I read a few things saying to "tune" the head to a certain pitch, I think I read A and A# at two different places. I mentioned this to the same two experts and they both kind of replied "yeah, right, pull the other one".
I am one of the least detail oriented people I know, but my thinking is that a torque wrench would be the equivalent of an electronic tuner for the head, as long as you knew what it should be torqued to.