I know I'm shameful
He's huge!!!!!!!
I imagine, knowing your history, that you mainly know pro cycling through L.A. in the TDF but I'd really recommend that you start watching at least the other Grand Tours and the Spring Classics such as Paris Roubaix and the Tour of Flanders - they are amazing races. Get yourself a subscription to Eurosport Player and you can watch lots of races not shown on mainstream channels.
Big Mig was a fine example of how much muscle you can pack into under 13 stone if your body fat is low! When he first started as a pro he was about a stone and a half heavier and too flabby to climb well but his coach put him on a diet and it transformed him.
Fabian Cancellara is another powerhouse, who just happens to be exactly my height and my
(target!) weight so just a smidge smaller than you.
Sean Yates (again - maybe 'a bit before your time') was another 6-and-a-bit footer, 12-and-a-half stoner and a mighty powerhouse who could tow the peloton at a high speed for hours at a time.
The most spectacular of the larger pros was
Eddy Merckx who was nicknamed The Cannibal because he like to 'eat up' his rivals and win everything, and he did!
I find those big guys inspiring because I find it hard to relate to tiny climbers, even though I love to see what they can do.
Climbing is 99% about power-to-weight ratio. People of our size and body type will never be able (safely) to get our weight much below 12-stone-something. You've already got your weight into the target zone, so now you just have to boost the power side of the power-to-weight ratio. I think that you could be a force to be reckoned with on the climbs if you continue to work at it.