Zodiackillersite.com

1948 sounds like a likelihood, seeing as he was retired from the military. If he did 20 years coming right out of high school, that would put him in Vallejo around '68

I probably won't have any luck, but I'm going to scour the interwebz to see if I can find any James Owens from Michigan, born around 1930'ish

This is a photo of him from the 1950's or 60's(publicly available on the net)

His obituary reads in part:

James Alford Owen was born on June 14, 1930 in Kalamazoo, Michigan. He married the love of his life, Verna Larsen on June 10, 1950. During the next 62 years they raised three children; two sons, Kenneth and Timothy, and a daughter, Laura.

Jim entered into the United States Army at 17, at the end of WWII, and became a member of the Air Force when it first separated from the Army Air Corp. and served proudly for 20 years. He retired from the Air Force with many distinguishing honors, not the least, becoming one of the original Chief Master Sergeants after the rank of E-9 was created. The Owen family traveled all over the world during this time. Jim was able to give his children an education of a life time and by this teaching them the appreciation of living in the United States.

Shortly after retiring from his military service he accepted a position at a new oil refinery being built in Benicia, California by Humble Oil, later renamed to Exxon Oil Co. He rapidly was promoted to supervisor, superintendent, safety director and finally Director of Risk Management. Jim took great pride by working with his son, Timothy, at the same refinery.

After retiring for a second time, he took a director’s position for a large construction company in northern California until finally agreeing with his wife that it was time to stop his work career, or so it would seem. Years later he worked for a short period of time off the coast of southern California working back on the oil platforms.

Doesn't say what part of northern California, or where exactly off the coast of southern California, but it seems he moved around California a lot.
He also has ties to Rosholt, South Dakota as that is where his mother in law lived.

His memorial service was performed in Las Vegas, Nv

There are several pictures of him here...but most are his later years in life.

http://obits.dignitymemorial.com/dignity-memorial/obituary.aspx?n=James-Owen&lc=1009&pid=159317878&uuid=39c0522d-70e7-445b-8367-edc4183662c2