'Grats on the pick-up!
I have a white one with no-date, in fact, I have two other no-dates in black. I think yours looks nice!
I was afraid to buy a 'date' version because of the offset cannon pinion in those which is supposedly highly prone to wear, and hard to find. I've never heard of anyone on our Forum mention an issue with these, although W&W thinks it's significant:
http://wornandwound.com/review/affordable-vintage-zodiac-sea-wolf/
I can't help you on the date range, but looks to be similar age as mine, which I believe is probably early-mid 60's.
Here's some old ads you may have already seen in some other threads, but re-posted for enjoyment here:
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And here's my 'whitey':
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