If your valves seating properly is an issue, or you think it's an issue, you could try "lapping" them.
In my younger years I would do my own valve jobs this way when I was too cheap, oops I mean broke to pay a shop to do it.
Lapping the valves is a process of freshening up the mating surfaces.
This is easily done in your own shop by removing the retainer and spring, then getting a small can of valve grinding compound, fine and course at opposite sides of the same can, and a nifty little tool that is a straight rod with a suction cup on each end.
Smear a little compound on the sealing surface of the valve, put it in the hole, then put the suction cup on the valve. Then, using 2 hands you put them against the suction cup rod and run your hands in opposite directions, rotating the valve back and forth quickly.
This process cleans up the mating surfaces quite nicely. Start with coarse, finish with fine.
And it gives a visual of the 2 surfaces so you can see the contact area. If a valve is deformed or a seat is kaput, you will see it.
The mating surfaces should be nice and even.
I have done this process on scores of engines prior to having the money to take the heads to a machine shop. It works on all engines, big and small.
Ah the memories of my youth!
