This is a hard one to value as most people will not pay a pittance for the upper or the bolt. The VQ lower is worth much more than the upper and bolt combined. But the market for the bolts has fallen due to Volquartsen selling new Mark IV bolts on eBay for $40 or less. Just crushed the market for bolts. I ended up with four of the Mark IV bolts, two with new Volquartsen internals, for $130 total.
Volquartsen did the same thing with pencil Mark IV uppers, selling them for as little as $35 delivered to the FFL in the Ruger packaging. The Mark IV upper does not impact the Mark II market much, but the Mark IV bolts do as the new bolts work in the Mark II and Mark III (once the loaded chamber indicator is neutered).
The other negative for that combo is most people want the heavier barrel even though I admit to being quite fond of the pencil barrels, with the old RST-6 my favorite.
My best guess is that getting $600 out of the pistol will be hard, with the frame and mainspring housing driving most of that price.