Agree about Red Bridge onward.
woodway nailed it as to conditions on 9738. I have done that one. It gets steep in places and rough in places too. 9702 is just as rough in places although it seems to miss the super steep parts. The problem on the west side of Red Top is the roads are all gated, have not been used in years so may or may not be passable. May have numerous downed trees. Lots of dead end spurs as well. If you chose either of these two options you will miss the Swauk Prairie. Each way has it's own beauty. I am so familiar that I take it for granted. The geology of the Teanaway is dissimilar from elsewhere in my region. About as pretty as a mountain valley as you will find east slope of the cascades.
Another thought, and you likely have already thought this through but once you are past Ingall's Creek on the north side of Blewett there is no water until Mineral Springs, a store or a USFS campground. If you are travelling with a water purifying pump there will be plenty of opportunities to fill bottles. Often when I have ridden to that area from home I would drive up and drop cache of water in strategic locations beforehand. I now have a water pump that I will carry.