Wilks is a Brand Value level 2 (BV2) maker's name. The gun sounds like Original Quality grade six (OQ6 = Plain SLNE/2nd quality BLE). Is it an ejector gun? And, it sounds like Current Condition level five (CC5) per the following table.
Current
Condition Definition
1 Pristine = top one gun of one hundred like guns
2 Limited use - slight finish wear, little shooting
3 Significent use
4 Heavy use, but no abuse
5 Minor repairs needed or restoration accomplished
6 Shootable but needs some repairs and refinishing
7 Shootable but needs repairs or restoration
8 Marginally shootable, significent repairs required soon
9 Unshootable without major repairs/wallhanger
So, BV2-OQ6-CC5 = $2,000 for a 12 gauge SXS of 1890ish to 1960ish vintage at USA retail. The 28 gauge will add a premium of say 1.25 to 1.75 ; the price should fall into the $2,500 to $3,500 range. Post photos and I should be able to narrow down this range. BTW, I imagine it is a 2 1/2" chambered gun.