Welcome.
Don't think anyone here (or anywhere else) can put an estimate on something we can't see.
Photos in natural light (shaded) usually work the best.
Interesting that you say the barrel bands match, yet the stock has been swapped.
That is an uncommon occurrence.
Are the stock and handguard numbered at all (in the barrel channel)?
Get a few photos, post them to Imgur or some other photo hosting place, and downsize the photos so that you can post them here.
If not, you can always go to gunbroker.com and peruse the listings there for a relative value based on what you know you have (condition wise).
Do remember that the prices you see are asking prices, not necessarily selling prices.
Looking forward to seeing those photos.
JT