8 and 1/2 feet, at least. We use 8'2" Boss's, and I would like them to be wider, ie. 8'6". Get a vee plow of any brand (except Meyer), and enjoy. Your truck won't mind the size or weight, and your pocketbook will appreciate the productivity.
Regarding the lift, the key snow plow aspect to respect is that the A-fame of the truck should be level when the blade is on the ground. You would probably have to have some customization done to your mounting kit, because I don't think there is that much adjustment in any plow kit available. Don't be tempted to modify the blade itself -- modify the frame kit. Kits can come and go, but you may transfer the blade to other vehicles in the future.