Parts replacement is the last option.
Python parts are very expensive, then they need a real Master pistolsmith like Frank Glenn do the replacement and fitting.
Barrels and especially cylinders are very definitely NOT drop in parts, and it's usually a major mistake to trust a local general gunsmith to do this level of work.
The refinishing question comes down to how bad the pitting really is. A real Master polisher can often do amazing work.
If the pitting is bad enough there may still be some left even after a master level polish job.
In any case you have to be very careful who you have do the work, and they'll have to actually have the gun to examine before being able to say what they can do with it.
Whether the barrel or cylinder might have apparent metal removed is related to how deep the pits are and how well the polisher can blend the removal in with the rest of the part.
If significant metal has to be polished off the stamps might need to be re-worked. This is usually done by hand engraving to restore letters and other stamps.
A blued gun can be bright nickel plated, but since bright nickel plating will make any defect look more apparent, you might be better off to stay with bright blue.
If you want a refinish in my other post above I listed some real experts who do nickel.
Here's some experts on bright polish bluing you might contact......
The same cautions about Ford's as above hold. Ford's used to be famous for being able to do a top quality Royal Blue with the 50's Colt wet look. If they've corrected their problems they should be great, but until I hear more current feed back it's buyer beware.
https://www.fordsguns.com/
Glenrock is famous in the trade for quality bluing and they offer a high mirror polish. They're used by many custom gunsmiths who need top of the line work for high end custom guns.
http://www.gunbluing.com/
Also as above, the Custom Shop is NOT connected in any way with the Colt Custom Shop and Colt only listed them as a possible source for Colt gunsmithing and refinishing.
Some reviews and the pictures on their web site look good.
https://www.customshopinc.com/
Ron's is a higher end firearms restoration service. Since the best, Doug Turnbull apparently no longer do Pythons this might be a good choice.
http://www.ronsgunshop.com/
Homestead recently got a recommendation on the forum. I know nothing about them.
Firearm Refinish and Restoration
Smith Gun has a good reputation.
Smith Gun ? Professional Gunsmithing
Last, for a shooter you might consider having your Python hard chrome plated. This is still the best all around gun finish and is one of the very few that's a true lifetime finish.
Probably the best at hard chrome work is APW-Cogan, but I'm not sure about pit removal.
One advantage of matte hard chrome is that it makes pits less apparent.