Get to know a welder- you won't make the fortec mount work with that monster. I have a 6 ft andrew x-band alum. dish, and I'm in the same boat. My
Cband mesh dish has a beefy mount, but even that's too light for the 70+ lbs of the andrew, much less the wind load.
I'd scale up a picture of a polar mount, and use 1/4" or better thoughout.
Larry