I run the 29er version of the Magic 80 on one of my bikes. I weigh in at 185 so I don't know how much help I will be for you. Even at 185, I had a hard time setting this fork up, and I am still not 100% thrilled with it because fo the following;

1. To get the nice plush feeling I want, the IMV does not work as well as I would like it
2. To get the IMV working the way I would like to to, I have to run a higher pressure than I would like, making the fork ride a bit harsh.

I usually opt for #2, since I do mostly fast XC rides. But, I figured it would do both when I got it, Act plush and Act as a lockout. I can't quite get it to do both.

Originally, I asked for help on the MTBR site , and I received a PM from the WB rep ask me if I needed help. I forgot his name (darren I think?) but he was a nice guy.

Bottom line, on setup, you should have the fork set up to go through its full travel during the course of your ride.

For me, I set it up with the IMV valve at about 50%, then adjust the air so that it rides the way I want it to. Then, I crank up the IMV valve to where I think the threshold should be. Then play around with the rebound and compression from there. WB told me that it was most important to set the air pressure first before playing around to much with the IMV. At your size, the air pressure will be a tough thing to fine tune, because at the higher end of the pressure, 85+, small adjustments have a huge effect.

Good luck.