oil on spark plug

We ll I just freshened my boys 440 in his demon. Went to the track and after a few runs it started smoking blue out of the right side, pulled the plugs all looked great till #7 wet oil on it. Heads were re-worked at the time of refresh. I thought maybe an oil ring got messed up so I pulled the piston and it is fine, but I put a new oil ring on just in case. Put it back together and same issue, I'm thinking head issue? Any thoughts? Thanks