I have two sets of heads one is stock and the other that are currently on the motor are iron mountain heads. I can see day light through the stock set and suspect that the iron mountain heads are leaking as well, would lapping the valves on either set help or do they both need to be re-cut? Thanks.

The seats are likely warped. Lapping them may help a little, for a short period of time, but it is definitely better to have the seats re-worked.

Ok, so If I go that route where can I buy one piece valves.

PVT