We're all older
Just depends when you stop counting.
I wouldn't second-guess any of the upgrades you made. Especially the chainring swap -- 22x34 sounds like you're planning to climb the Himalayas, but you have special circumstance that I wouldn't know how to adapt to. I'm impressed....
Changing to longer/taller stems is a standard way of moving up or down a half-size on the frame. Shouldn't be a problem. Where do you get 40h hubs and rims??? Even the stock of 48h is dwindling, and 40h have always seemed 10 times rarer. I'd just stick with 36h, unless you really are planning a year over the Himalayas (in which case I'd get 48h). Your front wheel excepted, since it's on hand already. I might be wrong, but 36h are relatively easy to find in case you have a wheel problem.
I've got a new Terry Liberator saddle, but I haven't put enough miles on it to evaluate. Never had a Brooks. Even so, I couldn't comment (everybody's butt is different....)
As for barcons, each rider has his/her preferences. But I find them superbly easy to shift -- doesn't even take a thought on my part, and no weight shifting on the saddle. But I don't like the standard cable routing for the Shimano barcons, which as you observe kinda interferes with the visual appeal and handlebar bags. I like to route the cables up around the first handlebar bend to the brake levers, then off the bars and down. Like Suntour did with the original barcons. Looks better, and never a problem with a handlebar bag. The problem is, the Shimano stock cable housings are too short, so you have to make your own.
Anyway, try the barcons for a while. They take getting used to, but maybe after a couple rides you'll find 'em well suited. Changing shifters can be almost as expensive as swapping cranksets....
Congrats for getting back on the road! Happy riding.
-- Mark