The fork bridge (or brace) on the 650 models requires the special fork lowers (legs) which have the fixing points for the brace. You have 3 options:
1. Easiest option is to fit an aftermarket brace to your existing forks as shown in elrodicator’s picture above.
2. Get some 650 forks with the brace and use them
3. Similar to 2 but all you actually need from the 650 is the fork lowers + brace, the rest of the fork components are, I think, interchangeable.