Like Cyclebum, if I avoided all the shoulderless chipseal 60 mph roads around here, there wouldn't be a lot of places for me to ride. What makes them rideable is relatively sparse traffic. That, to me, would be the deciding factor in whether or not to attempt those roads. If there's a bike store in the area of that road, I'd try contacting it and asking for their advice on routing and the road's rideability.