I'll concur on the matter of legality. It's only o.k. from private buying from dealer in a adjoining state. I ...BELIEVE....One of yall can go to the other state and do the transfer through a dealer though.
As far as the value, I've seen better, and I've seen worse. If this is from someone you know, and can confirm the history, that holds a certain value over someone you don't know telling you, as his word doesn't necessarily have any worth. I'd confirm whether it's a USGI synth. or oversized synth. If oversized, it's likely a Mcmillan, and valued at or around $350-400. The ARMS is at least $100, and the accuracy work is probably at least another $100. If it were me, I'd consider the base rifle valued at $1000, or $900 at a dal price, and then add the resale value of the other items to that figure to see if I felt I was getting a fair or good or great deal. FWIW, I have seen some National Match, not just loaded, but real NM rifles sell for $1500, and even preban mostly USGI parts, except for the barrel.
You might want to check gunsamerica's M14 and SA rifles sections for some price references.
As others said, you're not getting taken, but a better deal could be had.
Also, FWIW, I sold a USMC built NM to a ex-USMC competitive shooter for $1500, and it was built to the max. Needed a new barrel soon, but the buyer sent me some targets and it was shooting 0.993" 3 shot groups at 200m with irons. He shot with USMC competitively in the mid 80's when the rifle I had was built. He knew several USMC armorers from the timeframe and was still good friends with the guy that kept his rifle up. He wanted one , more or leass, for old times sake, so I did give him a bit of a deal. The rifle was all USGI with a HR NM trigger group, TRW bolt, preban receiver with rear lug added by USMC, welded unitized gas system, steel bedded in a early camo'd Mcmillan oversize stock, with a USMC marked Lite heavy 4 groove 1-12 twist barrel. Needless to say, I kinda regret selling it, but I had picked it up at a pawn shop for cheap, and just bought it to resell. Point is, there are deals out there if you really want to find one.