The GB Maes bars on my Grubb are 40cm c-c at the bar ends, but the problem that I had to get used to was the short "deck" or flat part at top. They begin their bend 12cm from the stem, where-as my 40cm Scott Liteflites give a "deck" of 15.25cm on each side of the stem.
I'm slowly getting used to it, though. I think that's the secret. Give the period-correct bars a chance to acclimate to.