You'll have to clean, rebuild, and restore any part of the bike that touches raw fuel. Tank, petcock, lines and carbs.
By the time you address tires, chain, carbs, tank, battery, brake lines, fork seals, and electrical restoration, figure you'll add another $1000 after the initial purchase.
$1700 isn't bad for this bike after it has been restored to reliability. But, if there's anything you wish to change on the bike you haven't told us about, be sure to add that to the finished usable bike.
Wheel bearings? Steering head bearings? Seat cover?
Cheers,