All a bit of a guess on mt part but 'i think' it Won't be head gasket even if its leaking--there's leaking & leaking--if it blew totally it'd stop but if it's just showing signs of oil mix after a run just tighten the head down. Won't be enough to draw air in. My guess is the crank seal behind the mag. Or something restricting the pilot jet. With reeds you can often see daylight under them but are forced shut when piston is on the way down.

+1 on crank seal. 

Stock reeds are likely fine
 

Are you running a good air filter?  Reeds generally aren't "noisy"...  might be piston wear? 

Wonder if the reeds are 'Squawking' like a duck from being turned over & bent slightly so now forced hard onto the seats. Won't be a problem. I'm just remembering when reeds first arrived in "72 & bikes were squawking away in the shop on kicking them over. Not sure about when running but maybe you'd hear it at idle. Wouldn't worry [if its that].