Vintage Hansen shortboard - 6'5" with hard rails, I'm guessing early to mid 1970s?

I picked this board up yesterday, found it on craiglist.  Its 6’5", about 20" wide, and about 2 7/8" thick.  Its got nice color and isn’t in bad condition, though it needed a few repairs (in progress).  It doesn’t have a leash plug, and it has a down rail design from nose to tail.  I’m guessing it is from the early to mid 1970s, but I really have no idea.  The fin box looks original, and appears to be the same as on my modern boards.  The fin that is on it doesn’t look original, and I may replace it with a 7" Greenough A4, though I am open to suggestions (is there a rule of thumb for fin size?)  I can’t wait to get it watertight and surf it.  Anyone got a guess as to how old it is, or any other info they would like to share?  




My guess would be 1972, or 1973.    By then Hansen had gone to the FU standard box.     The leash plug, or through the box method had not yet become popular, at that time.

Thanks Bill.  You’d be the man to know!  

edit:

Did these boards come with a fin from the factory, or did the buyer just pick out a fin they liked fromt he surf shop?  

[quote="$1"] Did these boards come with a fin from the factory, or did the buyer just pick out a fin they liked from the surf shop?   [/quote]

I don't know what the Hansen policy was at that time, so can offer no insight.   I had stepped away from the industry, in those years.

I had ashop in NJ in the early 70's As I recall boards were shipped with a standred fin, Something that matched the boards color. but people would swap out fins or buy thier own if they wanted something diffrent.

Thanks for the info!