So I got this great '74 Gitane Tour de France and I was surprised to see it came with 27" wheels. (i guess I didn't do my research) Anyways, I'd love to get my 700s on there, for a wider range of tire options, and just to update it a little, but even with the 27" wheels, the rear brake is maxed out. It's a Shimano600 Arabesque caliper (matches all the other components) so I dont want to replace it, plus, it appears to be at 57mm, which is standard long reach (right?)

Unless I can get a longer reach Shimano600 caliper that matches - is there any way of extending the reach? Is there such a thing as an offset brake pad, or a jogged mounting bolt of some kind that I can get the extra 1/8" that I need?

Thanks!!
Shane