Welcome to the site !!
It sounds like you have covered most things .... What I would add , is look the clutch basket over for grooving , if it is grooved , it is eventually going to need replacing , you can file it down to limp it along for a while (maybe 1 riding season) , but eventually the grooving will come back as the plates will have more room to slop back/forth because of filing it
As far as the clutch side of the case , you can use brake cleaner and some air to clear it out of debris , wipe out what you can , then spray the cleaner , then wipe , then spray again , till you don't notice any dirt .... then let it dry and blow with air to get into any crevice you may have missed , like near the seals , etc , , I would also tear into the carb , pull the bowl and see how it looks inside , if it is green , or shows any signs of dirt or contamination , then I would clean it thoroughly , if there is any remaining gas in the tank , drain it , and wait till you are ready to run it again , before buying any for it , you always want FRESH gas in these bikes
, if it sat for more than 2 months , most likely the gas is bad and the carb/jets clogged .......... other than that , it sounds like you have thought everything out and are on the right track ........ Good luck .... and if you have any concerns or more questions , just ask .....