I normally don't dismantle an engine without a reason. If the piston and rings are good (viewed through the ports) and the compression is good, I'd be looking for evidence of leaky crankcase seals or gaskets. Try to assess the main and big end bearings for slack by feeling for movement. If it came through all that evaluation well, I'd run it to see how it sounds and then start the tidy-up job on the carburetor and probably some other parts. I personally don't remove even cylinder heads routinely, I only do it for a reason. Those comments are for a mower engine. Chainsaw and brushcutter engines I am even more reluctant to dismantle because most of them seem to be made out of snap-on plastics and tin twist-tabs that will not survive servicing. I think your machine is of a higher calibre than that but unless it was part of a restoration, I'd only dismantle bits I had to service. For example, when you start it you'll see whether it is pumping bar oil. If it is, I wouldn't clean out the oil passages downstream of the pump, I'd let it clean them itself by pumping oil through them.
I understand that saw uses a fairly unusual design of centrifugal clutch, and with parts difficult to get, I'd begin by seeing if the clutch works. If it does, and its bearings are good, I think I'd leave it be for now.
