Congrats on inheriting such a classic...
I hope to pass mine on to a family member when I am gone.
I recently found a similar 1680 (meters first, not feet first like yours) and had it cleaned up a bit.
The threads are here:
http://www.rolexforums.com/showthread.php?t=72504
http://www.rolexforums.com/showthread.php?t=73324
http://www.rolexforums.com/showthread.php?t=73952
I'd say your 1680 is probably around a 1972, need the serial numer and a clear photo of the caseback would be nice. The triplock crown was a replacement and the 9315 bracelet is period correct but if sold in the US probably came with a C&I instead.
I know a watchmaker in Oregon that does excellent work and he did mine for under $500 US; check out the photos.