Originally Posted by
stardognine
As far as dating it, I'd think late '80s or early '90s, with that non-lugged steel fork.
According to vintagecannondale.com, the logo on this frame's head tube was in use from '83 through '89. To narrow it down to a specific year, the OP can cross-reference his the serial number to the info on that site :
Vintage Cannondale ? Serial Numbers & Information | VintageCannondale.com
Depending on the year made, the serial number may also give some other information like production date, frame size, and dropout spacing. (Although you've already got most of that stuff figured out.)