Cantilever fork boss... too narrow?

I'm rebuilding an old CX frame (see here) and I got some second Avid Shorty 6's from a friend.

The problem is they don't fit. It's like the bosses on the forks are two narrow and the pads won't hit the rim properly. It was using Shimano 600 Arabesque canti's originally and they fitted fine.

Does anyone know of a similar, more modern, canti that looks and works like these? Tektro CR720 are a no-go. Too wide.

EDIT: I don't want V-Brakes and I'm running Rival shifters / brakes.

What's wrong with the Shimano brakes you were using?

I want black brakes to match the rest of the groupset.

I'll run the Shimano ones for now.

http://www.chainreactioncycles.com/Models.aspx?ModelID=27940

I thought I'd bump this thread as I have the same problem, but have not been able to find much conclusive information...

I have an 80s Gitane Cyclocross with fork bosses spaced at 55mm, I believe the modern standard is around 70mm, so quite a difference. Ideally I'd like to use a modern brake, and have tried the Tektro CR720s with narrow pads and spacers removed, but still can't get the pad square with the rim.

It seems the old-style brakes don't have the v-brake style adjusters used on modern pads:

I've read a few threads on the Internet where people have the same problem, but none where anyone has come back with a modern model with geometry that also works for the old narrow spacing.

Maybe the Paul "Neo Retro" would work (I have emailed them to ask)? Ideally I'd like something cheaper.

Can anyone recommend a model they know to have worked? I'd like to use a wide-profile style if possible...

http://www.wiggle.co.uk/shimano-ultegra-br-cx70-cyclocross-cantilever-brake/

would these work? they have that massive spacer between the pad and body you could remove, and i think they do a cheaper version in same style

http://item.mobileweb.ebay.co.uk/viewitem?sbk=1&nav=SEARCH&itemId=271059426355

I had the same issue with my 80's mercian tourer ended up using a set of these above.
Couldn't find anything modern and didn't want to buy several options to test. With koolstop pads the are decent.

Would be interested to hear if anyone has better options!

I have a set of frogslegs-alikes that will work if you are interested?

I ended up using Frogglegs. They seem to work okay.

Thanks for the feedback. Seems like froglegs are an option.

I got e-mails back from Velo-Orange and Paul Components saying that their models did not fit with the narrow width.

I'd be interested in hearing about any of these:Dia Compe GC-999, Dia Compe CRX or TPR EuroX These seem to be traditional designs based on the post-mount rather than threaded v-brake style blocks. Which maybe have more room for maneuverability.