When I get my cylenders back from Jeff at FAST I will basically have the same setup as you. I opted to stay with the stock crank though. I do the same type of riding as you, trails and drag. I wanted something that worked well for both. My mods will be 50 over stock stroke, dune/play port with 33 PWK's and pro circuits, K&N's. I'm going to stay with the milled head for now, but when I get the funds I'm going to a cool head.
My guess would be 33-35's. Shoot me a PM in a couple weeks if I have it running I'll let you know how my 33's work out.