"a" leaking valve seal won't cause a bog in any way that I can think of..... on guide knurling, I've seen it done, many times but given the less than stock surface area you have in the guides now to actually "guide the valve" and what you do have is raised/displaced much like cutting threads, it is a "weaker" repair than just reaming a little more oversized so they can press a real guide into place. so what Im saying is it'll be OK for a while but won't last as long as putting in a replacement guide.
