Well this didn't work out just exactly perfectly. I picked up a fuel filter and a spark plug for my cousin, but took a pass on a new air filter, figuring I would just wash it in soap & water for him.
Although my cousin did know to clean the air filter occasionally, he would just blow the sawdust off of it with compressed air. The actual filter material was now so quite largely black in color I figured it was probably too late to accomplish much by washing it. Next time I am down there I will stop at the saw shop for him again.
I did luck out in that this project motivated me to finally pick up some files for .325 chain (people I visit often have no idea how to sharpen their saw), but that didn't matter because he (or dealer, or previous owner, not sure) had already modded this saw to 3/8" anyway; the same as I run.
His bar was only 1.5 firewood seasons old and in relatively new condition, but already in need of dressing. Pretty sure it had never been flipped. I did what I could with a flat file but I told him to take it to a real saw shop to get dressed. That will never happen; no such shop in his county.
He does sharpen chain pretty effectively with a grinder, but has totally erratic results trying to use it on the depth gauges by just guessing. So I did those for him with the proper measurement on his relatively new chain and that will help him quite a bit.
Overall his saw was better off than some weekend warrior editions I save for people, but I am a little bummed I didn't just pick up a filter for him when I was standing at the parts counter. I should have known it would just straight need a new one.