I actually really like the cycle. It must have cost you an arm and a leg for all that anavar, but 100mg/ed is a great dose that's for sure.
For the arimidex... you could just use it (weeks 1 - 12) @ 0.25mg/E3.5D
Discontinue the arimidex before you begin your PCT... also, if you're going to be only using clomid for your PCT and not nolvadex, you should drop the clomid dose, and run it longer (IE)
week #1-2: 100mg/ed
#3-4: 75mg/ed
#5: 50mg/ed
I'd be interested in seeing some pictures. 280 and 6'4 is a big frame to work with. post some up if you've got em'..
Hope that helps..
-VM