It might be possible to grow it in Silicone Valley in most winters if it was given a little bit of protection such as frost cloth. My Physical Graffiti got damaged badly this past winter, maybe killed completely, after going through 35 mornings with frost and getting down to 22F one morning. I would select Paul Thomson's 8-S or 'Houghton' (one of the parents used to develop 8-S) since both of my plants of that survived the winter fairly well and produce excellent-tasting fruit, albeit small (maybe 5-6 ounces). I will use my P.G. cuttings for my own needs and don't have any extra of the other two either, but you could write to Linda at
Dragonfruit and she would probably sell you cuttings by mail of 8-S (she calls S-8 like many other people since Paul apparently spoke of it with this name but wrote in his book that it was called 8-S, the "S" standing for "seedling").
Giant Vietnamese also survived my winter very well but the fruit is not so tasty. Okay, I'll say I've never found it to be very interesting.
I think Paul's 'Delight' might be fairly hardy since it had one H. undatus parent and it tastes pretty nice. I just have one small plant of it as the original one I got wasn't labeled correctly, I believe.