For the record...
Interarms -- here in Alexandria VA -- sold both Zastava and Whitworth rifles that were made in Kragujevac Yugosalvia -- now Serbia -- but shipped only as actions or barreleled actions.
The Whitworth company in Manchester England,bought actions, rebarreled them IIRC and gave the actiosn more final finishing. They are thus a bit smoother and desirable. From Manchester, they sold some barreled actions to Interarms which did the restocking here with Italian made stocks and marketed the finished rifles in the US. Whitworth restocked others for sale elsewhere.
Most were made in standard calibers like the .30-06 and .270 and the .375 H#H and a few .300 H&Hs. I do not think that they ever made many if any .280 Rems so the barrel on yours could well be a rarity or, more likely, an aftermarket item.
They are sound rifles.
My gunsmith used to work on the Interarms assembly of these rifles and still works in the original warehouse area.
1B
The Interarms are commonly used as donor actions for custom builds. If they never made a .280 that's likely what this is. At $300, I'd buy it.
