I would also suggest another opinion. I would not rule out surgery, as you know tears are a PIA. My first surgery was in 1975 and feel blessed that the approach has changed dramatically since then. I too am not sure why they are suggesting a brace for cycling, rehab and a good PT will do more than a brace. Cycle Oregon is a great ride, don't rule it out yet and perhaps give yourself permission to attend with no expectations of "How fast you complete each day" If you go, just enjoy it, give yourself permission to take a sag wagon day if need be. I was down for 18 months with severe achilles tendonitis in both tendons and am just now to the point I can ride consecutive days and one thing it taught me is to let go, enjoy the moment and take nothing for granted.
Take care we are ALL on your side!