Yes, I'll clean the top of the piston and combustion chamber from time to time. You don't need a torque wrench because the B&S flathead is not that picky. An 8-inch long 3/8'' drive ratchet is fine going by feel. Just make sure you use the proper torque sequence.
I clean the top of the piston using WD-40 combined with a Dremel wire cup wheel. The trick is to keep the piston wet with WD-40 as you're running the wire wheel over it. When you see a black carbon soup over your piston, you're doing is right. Use the wire wheel on low speed.
I clean the combustion chamber with the same wire cup wheel and WD-40 the same way as I clean the top of the piston.
I also clean the intake and exhaust ports, but you gotta be careful not to rub the ports with the metal shroud of the wire wheel. I also stuff a little piece of Scotch-Brite in there and twist it around to help clean too. Obviously it's best to do this with the valves removed.
If someone was to invent a ball shaped Scotch-Brite attachment for the Dremel, that would be perfect.