I agree with Drew, you should make sure that ol' guy knows you appreciate his gift by putting it on your engine and take it to show him. You also need to pick his brain for his knowledge. I'll bet he'd be more than happy to sit with a cup of coffee and share all he knows.
I wouldn't mill the head, before you find out if it needs to be milled at all. Then, when you do install it, be sure to check for your valve-to head clearance. You can do that with a dial indicator, or use modeling clay, like we used to do in 'the old days'
Congratulations on your new friend!
