I see that you're a month older than me so we're pretty close in age. I'd like to attain to your level of cycling activity, but I've only been back on the bike for 6 months to date and I'm still dreaming. However, your post gives me a lot of inspiration. Maybe when I get to 73 I could also become a "monster" like your mate. I love the hills too. I do have an ongoing medical problem with Polymyalgia but apart from that - no hassles. Still on my old bike (1959 Helyett), but seriously cosidering a Giant OCR 1 to replace it. Then the Helyett is going to become a fixie. More dreaming.
Cheers