Melvin, the cable stop on the seat bolt won't work as the rear end moves so the cable will get slack when the suspension is in full compression (bit like a headset mounted cable stop on a sus fork). Those cams are still around, try some of the folding bike shops (bike friday, brompton etc) or go to http://www.sjscycles.co.uk/product-SJSC-Pashley-APB-V-Brake-to-cantilever-conversion-kit-(cantilevers-not-included)-7174.htm
for a massively expensive version (you can normally get them in for $10 in most shops)
or just go magura for that herboldy feel!
Beautiful bike though, really pleased for you!
Thanks Pete for pointing me at it! Actually similar hapened to me with a front fork once, but now again for the rear
Proves the complicating systems aren't good for the people, but this one is a keeper though