That makes sense. That's around where I was thinking too. The leather band I would think would indicate farther back, not too close to the 1983 date. I've seen flat caps with, not sure if they're cotton or what the material is, but the softer non leather sweatbands which I would think are more recent. But the 1960's estimate sounds about right to me. Thanks for the reply.
Gustin Vintage Heavyweight Sweatshirt - Natural Rainbow Nep - $119 Rugged 14oz cotton that gets better with every wear. 
Grant Stone Diesel Boot Dark Olive Chromexcel - #395 Goodyear welted, Horween Chromexcel, classic good looks. 
Himel Bros. - The Ross Mk. 1 Leather Jacket Classic D-pocket motorcycle/aviator style jacket. This is very nice! There is a German cap-making book that features the same cap (unfortunately without the bill, No 3 in the manual above). Another template featured in this book (again without the bill):
