Not from your area and am not recommending anyone but just a few things to look for when evaluating a reblued firearm.

I am a graduate of PA Gunsmith School and was a self-employed Smith for over 5 years...Don't do it anymore but that's another story.

What to look for:

Blurred lettering: the lettering should be crisp, clear and present...! If a gun I was rebluing had pitting and I needed to draw file prior to polishing, I would never file over the lettering. I would rather leave some pits in those areas than deface factory lettering.

Funneled holes: If polished improperly the holes in the steel will be "funneled". In other words, they will not be flat and square with the surface of the steel. This condition is more commonly found on flat areas (Like the sides of the receiver of your 870). I always finished flat areas by hand with a sanding block. I never took the flat part of a receiver to the wheels...You are asking for funneled holes if you do.

Straight lines/Sharp edges: Shouldn't need much explaination here but suffice it to say that someone with a heavy hand at the wheels will not accomplish a finished job with straight lines and sharp edges. The best test is to pick up the piece and "sight down" the edges...Any wavy lines will pop out like a sore thumb. "Dulled" edges should be apparent.

Consistant blu, not cloudy: Take the gun and look at the whole piece, comparing curved surfaces with flat etc. View the gun under different light sources; the shop, out doors, florescent, incandesant, etc...Whatever light options you have. The bluing should be a consistant color with no cloudy areas.

ALWAYS ask to see work from the Smith who will be polishing your gun. Quality polishing is a difficult skill to master. More guns are destroyed by heavy handed "Smiths" than you would imagine.

If you are really concerned about the quality of polishing, you can always do it yourself, entirely by hand and then get the "white" gun reblued but that would be a whole other post describing how to correctly polish a gun by hand. BTW, that is how we polished our first blu job in school...from mill file to 600 grit...Big job but NO better way to get a 1st class polish job on a gun. It was a lesson in comparison...If your power polished guns could come close to your hand polished gun you were doing OK !!