Following O'Gorman's effort, openside flanker Kevin Curtis threaded lock Robert Gabriel through some weak defence at the 20 minute mark with a well-timed short ball.
O'Gorman also scored West Coast's third try.
King Country finally dotted down in the second half, when they had a furious final 15 minutes to give Coast a fright. First five Sean Cressy was the recipient of a wide ball from an attacking ruck after the visitors camped in their opponents' half. His try was followed by one to replacement back Dean Church after wing Simeli Koniferedi bamboozled Coast's outside backs.
But with the threat of a victory slipping from their grasp, Coast held on in the final five minutes.
West Coast 27 (R O'Gorman 2, R Gabriel, N Davy tries; C Deans pen, 2 cons), King Country 21 (S Cressy, D Church tries; K Strachan 3 pens; Cressy con).
HT: 15-6.