Here's my take. 610s are awesome revolvers stock or modified. Heck, I just bought another one today! My lust for them came after I was in a similar situation as you.
I had found this 610-2 four inch unfluted gun locally and after a little wheeling and dealing I was able to acquire it for a little over a grand. At first I was hesitant since it too, has had some work done to it (trigger/action work and a new front sight). When I inspected it in person it turned out to be in really nice mechanical and cosmetic condition. The work was claimed to of been done by Frank Glenn but there was no paperwork to confirm it, so I took a chance.
Not only did I get it way under value due to not having a box, not stock, non original rubber grips (that I replaced with Badgers) etc.. it's the nicest and best shooting post war N frame I own. I've had no issues with accuracy, light strikes, or timing.
Inspect the gun closely and if paperwork for the modifications can't be found then use that as negotiation to get a better price. If the seller is firm, I'd still roll the dice.
SVT28
Sent from my SM-G935V using Tapatalk