No expert; but I'd think 40 would be fair if it has the washer / screw that keeps the bolt in place. If not 25.
Again no expert; just what I'd ask / or expect to pay.
71 / 84's are neat but not nearly what a K-98 is worth. A parts gun would be worth 100 in my world; it's the price of a tank of fuel... like " Do you have that 50 cents you owe me?"
I had a fellow try to lowball me from 100 to 70 on a K-98 parts gun and I dropped the deal.
Not worth my time to wait for payment, box it, drive into town and mail it; to possibly get flak because it's not what they expected.
The hassle just isn't worth 100 $ to me.