I don't know the grade of the gun but twist barrels are most likely the lowest grade. Overall condition seems nice. Screws are good, no case hardening colours left, barrels show nice figure.
Appears that the butt stock may have been refinished and checkering re-cut. The wear on the forearm doesn't match the butt. Butt pad could fit a bit better. What about the inside of the barrels (measurements and pitting?) and length.
The original butt plate has a Neider point. So if your stock was cut flat to install the recoil pad it's not correct. If there is a V recess at the top of the stock you may be ok. However, from your pix it appears that the stock has been trimmed.
What you're considering is a Model 1889 grade 2 with normal to heavy wear and a modified stock. As there is nothing special about the gun the value is not great. If the bore is nice and clean, the solder on the ribs is tight, the barrels haven't been cut and the action is not loose I'd offer in the range of $225 - 275.
I'm looking so if you come across one with solid metal and decent bores drop me a line if you want to sell it whole. I don't mind doing stock work or replacing a stock. I don't mind refinishing metal but if it's lose or the bores are suspect no I am looking for a shooter