I have a cheap hardware retailed 20 ga double, it was left to me by my father, it needs extensive restoration, if price was not a problem, who could do the work.
Mike
Oh man have you opened on preverbial can of worms, and Pandora's box...on your quest.!!
NEVER, NEVER, Overestimate or Underestimate the value of a "hardware store" firearm!!!!.!
With that solved. Let's address what you are wanting or needing:
1. Restoration of a firearm for "sentimental" reasons. Agreed. Old guns deserve a well used life.
2. Old firearms have, share, and want...and deserve new memories; and all of those memories need to be shared.
3. Sometimes it's best to retire a firearm to the wall to reflect back on as to our, that is our individual memories and "our" roots.
Oh how I know your dilemma so very well!.
I'm not saying your dad's rifle is worth 100+% more now than when bought it. Nor am I sayi01ng it is now worth selling and going into early retirement for life.
Your firearm needs a deep dive into cost vs collector value vs you wanting to create new memories and handing it down to future generations of hunters.
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Now let's address what you are asking.
Depending on what the repairs are you are wanting most any competent gunsmith can do the repairs. If you are wanting custom work that is a whole nother story/quest and response required.
Please specify what You want? And why? If you want/require a proper response as you are vague in your request to increase or ....forbid you want decrease the value of a historical firearm.