[antonye]

I've done this on my 600ss and it was very easy.

Bought a pair of calipers off eBay (40mm spacing off an old 916) for £41.
Bought a pair of disks off Ali, which came from eBay, for £60.
Bought a new pair of forks (with the additional lug) off eBay.de for £113.
Bought a 916 master cylinder with braided hoses off eBay for £52, then sold the briaded hoses off it for £34.95.

I already had a pair of ACU compliant twin lines which I bought off Rattler for £40, so these went on.

Nice and easy - if I'd sold the original disk, brake system (m/c, line and caliper) and the forks then I'd probably have halved the cost.