Justin,
To see if this gun is indeed one of these contract guns, you should check the s/n to make sure it is in the correct range (1914ish).
As for if it's really worth that much? Like I said, I find a lot of his guns overpriced (IMHO) but it's only worth what someone else will pay for it. They are indeed quite scarce, and there is lot of blue left on the barrel / magtube, and it does appear in all original condition...but, $1700? Wow...maybe to a Winchester collector who is interested in ones that went to military contracts....
Concerning a replacement lever, I'm hoping someone else can pop on here and answer that. I wouldn't think it'd be much of a job if you can find a decent one off another beater maybe.
Matt