Thanks BT. The manual I have is a bit older than '79, so I'm glad you knew where to find one.I believe one of these manuals may get you close enough to help you out with a starting point.
You will need to join up with 4shared, And the other one also, But they are free to join, And they don't bug you with junk mail that I know of.
Throttle and Shift controls for all. 90-814705R03
http://www.4shared.com/account/file/144897617/4cfd9e4f/Merc_Controls_Newest_manual.html
The Password for the file is <<ribforum>>
http://rapidshare.com/files/213405838/105140jet-135-150-175-200-225.rar
From what I can tell from your serial number your engine was made in 1979?
http://www.maxrules.com/Merc_model_files/115-150.html
http://www.cdielectronics.com/downloads/troubleshooting%20guide/http://www.cdielectronics.com/downloads/troubleshooting guide/