Valve guide question

I recently bought a set of 920 heads for my 273. I have notice there to be more play with the valves in the guides then I feel comfortable with. I noticed some of the guides has rings in them, I assume knurling? I plan on doing gasket matching and some other work on the ports and bowls myself. Should I have the guide work done before or after the the bowl work? Also should I have bronze inserts put in the guides or something else done? What should I expect to pay for such work? Thoughts or suggestions?

Patrick