I generally use a modified version of the Steelers playbook. Steelers playbook, unaltered, is really run heavy, so I generall have a rusher up around the 1,500 yard mark. But my QB's do well too if they are good QB's. It's not the playbook that keeps me from throwing 4,000 yards a season, it the fact that I run most of the time.
I would imagine most playbooks that give a high completion percentage would come from those that have a lot of passing plays going to the RB and the TE's. Seems like a lot of the times those kinds of things are open over the middle. Most any West Coast system, like McCarthy, Reid, Shanahan and so on, should give you higher completion percentages. Playbooks made for deeper routes will likely lower the %. It's just easier to complete short passes than long ones from a % standpoint.
Better players, regardless of playbooks, will give you better results. If you stock up on talent across the board, you can go nuts passing or running with most any playbook. If you play it with more attention to the cap and building the team in the image you want, you get more realistic results. It's more the level of talent and how you actuall call the plays that matters, but it sounds like West Coast offenses are what you're looking for if you want to go the Montana route with your QB. Just make sure the QB has good accuracy ratings, or it won;t make a difference :P