[TomsSVX]

sounds like there is decent deformation on either the seat or the sealing surface of the valve... This can be due to a lot of things, more than likely the valve seats are burned or corroded which I have seen a number of times...

I have a crank to lap valves, but sometimes it will take grinding the valves and/or the seats to make everything right.

At this point, I would take the heads to a reputable machine shop to see about getting a valve job done, or you can buy a pair of my heads and let me deal with the headache.... Up to you

Tom