classic 300d have T2687 main brushes in them, the SAME for your SA200. Back in the early years some machines would accomodate T344 brushes, wider and thicker, BUT NOT ALL WILL. This brush covers more bars on your armature and is a harder brush. If your not the type to check your brushes everytime you change the oil (100hours) then I don't recommend it. It can and will cause problems.
You will hear something 'new' to do to these machines everyday. Be educated about your equipment. The next "tip" (and I use that term loosely) is that you can put a penny or nickel on your governor to make it run hotter. When all you are really doing is changing the govenor setting without having to turn a bolt.
If you are intersted in trying out the "tips" you learn in the field, YOU NEED A BACK UP MACHINE, to do this with. That way you learn on your own what the good and bad of this tips is all about.