Some USGI Import stamped carbines sell for $1,000.00. +
Commercial made carbines sell up to $1,000.00 if they have a few accessories.
A Fulton Armory receiver will cost ~$800.00
See he has the Inland marked as Original.
Also see the flip safety and late mag catch on the NPM, if the rest is original I'd consider a bundle purchase.
Offer $2400-$2500 for the set.
You get 2 carbines for $1200-$1250 each and he clears out 2 guns quickly.
You try them out and keep the best. Selling the other if you want.
You'll easily recover the cost with a likely profit per 1 carbine.
That's how I do it. I just haven't got the hang of the 'You can sell this part'
Keep us posted. Add more pics if you can.