Not having a picture of what you are asking about, I'll just say the best I can advise you is:
1. Check out the Seiko section of my database @http://seikoholics.yuku.com/forums/69/Japanese-Watch-Info-Database/Japanese-Watch-Info-Database#.VC9JZ1fhjNE
2. If what you are looking for is something that was marked "Officially Certified Chronometer" on the dial, and possibly also "KS" (King Seiko) in a squarish case, you are likely looking for an auto-wind calibre 562x family [5621, 5625, or 5626] OR 5245, 5246, or 5256 model from late '60s or '70s rather than early '60s. There are also some hand-wind 45 movement family 36Kbph models that were certified as well.
Try this section of the database for the non-KS marked examples:http://seikoholics.yuku.com/sreply/181/Seiko-Officially-Certified-Chronometer-NONKS-Catalog
The auto-wind KS marked ones are in another section of the same database:http://seikoholics.yuku.com/sreply/172/Seiko-King-Seiko-conventional-automatic
There is an example of a 45 Chronometer further down in the Seiko section as well.
3. If instead, you are looking for something marked Chronometer without "Officially Certified" on the dial, you are likely looking for an early '60s hand-wind model, but I've not seen those in square cases.
But, there were also "Seiko" [Hattori Corp.] models from much earlier (mid-20th century) that were hand-wind & marked "Chronometer" that are found in this section. Some may have been square cased, I don't remember off-hand:http://seikoholics.yuku.com/sreply/235/Seiko-Chronometers-PRE1960