possible stripped head holes

[nthnnxn]

Ok... So I've been chasing all kinds of oil leaks and I am down to 3 possible stripped head bolt holes (10mm), causing oil to pool up on top of the head. Confirmed the bolts are not the problem, but rather the holes inside soft metal head. I took 3 bolts from already known good holes and well torqued bolts, and then moved them to the known bad holes. The 3 bolts from the known bad holes torqued down well in the known good holes.
The 3 BAD holes are the 3 holes closest to the exhaust cam crank. I have tried putting sealant under the head of the 3 bolts...but they still leak. Is there a trick for the sealant thing to work? Should I take the head off for a helicoil, or have it done with the head still on? Is it possible the holes are NOT stripped and just simply need to be Removed and replaced?

Thanks in Advance!!