Ok time to chime in -- on taking the muffler nuts off the front -- spray them with WD40 or with another better penetrating oil -- let them sit, then spray them again for good measure (especially if they are well rusted).
Taking them off then should be no big deal. (If you do break one as has been mentioned they are not expensive). The "T" bolts fit into a slot in the cylinder which is behind the muffler (don't lose the conical washers on the muffler front -- you will need them when reassembling the saw). Then slide the muffler off (remove the front plate and spark arrestor screen and lay them aside first). The "T bolts" do not thread into the cylinder like pro saw fasteners, you angle them into the U slots and position them for the muffler to mount when assembling the saw.
At this point you should be looking at the gasket on the front of the cylinder- slide the muffler gasket it off as well. If the piston is not at the top, pull gently on the pull rope -- you should see then if it is scored or not as it rises into the exhaust window. If it is down you should be able to see the intake side of the cylinder (you may have to shine a flash light in now, depending on how well lit your shop is).
If you need to rebuild it because of scoring you might as well do several other things in the process.
(1). Plan on replacing the fuel line and impulse line (while you have it apart). It will amount to maybe $20.00 but you might as well while you have it apart and its "cheap insurance against engine failure (my opinion). Buy the genuine Stihl fuel and impulse lines -- they are great!
(2). Buy new oil seals for the crank case (Northwoodsaw.com is a recommended source). Buy the smaller thickness seals, and purchase a liquid gasket sealer that you will need to seal the crankcase/clam shell bottom. Many people here use Yamabond (believe Northwoodsaw has it as well.). Or if you're going hog wild - buy the pricey Dirko sold at the Stihl dealership.
(3). Since you seem to be planning a top end rebuild you might as well upgrade to the 039/MS390 piston and cylinder. It is a top end swap for your saw. You will be replacing the 029 (smaller piston jug etc.), with the largest top end in this series.
(4). Since there is an ongoing debate about quality I'm not going to recommend a source for the top end in the aftermarket realm. I would say that I have also seen used genuine Stihl engines and cylinders which are a good choice recently on Ebay.
If this is a learning experience for you, ignore the nay-sayers that say "don't rebuild the 029" it's heavy and you can do a pro saw and have more. If this guy wants to give you the saw that is toasted that is even better -- you can work on it in your spare time and ask questions in this thread. Plenty of help to be had here! Then you can rebuild it, mod the muffler, retune the carb and let the previous owner feel the difference when you're done! Hey that's my stump speech for an 029 upgrade (especially after that Obama "address to the nation" sheesh! what a load of cr*p).
Happy Sawing!
Enjoy the Journey!