Hmm I'm fairly certain I heard someone mention the R60s simply could not fit through the Brompton stem.
BTW it looks great except you haven't considered narrowing the bar?
AFAIK the std M-bar is 515mm wide so narrowing the bar by about 15-20mm on each end you could give yourself more clearance while still being wider than a Brompton handlebar. If you push your bike around regularly like me, there's bound to be a fair amount of tipping over and damaging the handlebar, especially given the new height.
I'm going to do something similar for my wife's new Brompton, and I'm still trying to decide how much to hack off her 700mm wide bar (75mm rise). Hers is an M-type (because the remaining S-type colors suck), so her handlebar will probably end up lowers than yours.