For what you have, $140 is a screamin' deal. A couple things...
First, while Wilson does decent work, 870s are so designed and made that they come apart and go together like Lego sets.
A couple here made in the 50s accept 2000 plus barrels with no glitches and other parts interchange freely.
So, you can mix and match parts to fit the mission.
Adding a 20" RS barrel gives you slug capability up the wazoo and a good barrel for when things go bump in the night. It WILL cost more than the shotgun.
I'd conserve those wear marks, replace that vintage plate with a newer Rempad and add a sling. Keep that barrel for wingshooting and clays, put on the short barrel at will and you have a versatile and effective goto for a pittance.
BTW, that Winchester plate is worth a few bucks to collectors. I beleive the grip cap is a replacement also.
Also, that wood furniture is what they termed the ADL model when it was introduced in 1950. My guess is yours is dated from before 1965. Let me know if I'm right. Thanks.
IMO, that's a 28" barrel and most likely choked Modified. Using a dime, see if it slides into the barrel. Most but not all 870 barrels of that period will not accept the dime if they are Full chokes.
Full of the period with barrels running .725 to .729" is about .690". A dime runs about .703-5", making it fit in the.710-715" Modified chokes of the time.
Note how the wear marks fall on the balance point. This was carried a lot and cherished by a prior custodian.
How do I know it was cherished?
No rust, no bangups from neglectful handling.
Take good care of this. It deserves it.....
HTH....