I'm on side with all this. Get it to cherry red all over, and either leave it to cool in air (which is what I did) or quench, makes no real odds. When it's been through that, it ought to be, noticeably, a zillion times more malleable than before you started, and will be ready to be squished again. As far as I know there is no limit to the number of times this can be done. But, like you Richard, I am sensitive to the eloquently-expressed and knowledgeable views of the fans of the composites, even though I'm not going there myself. I've done best part of 10,000 miles since I had head trouble last year, with a reused copper gasket, and no problems and no oil leaks (which is where I started too). But it's only a cooking GF engine! After all your hard work, do hope you find your studs etc are all in perfect shape.
Have to say that my A10 has become so extraordinarily first-kick reliable that I have nothing at the moment to say except - It's great! Wish other things hereabouts were as predictable . . .