Based on the style I'd guess early fifties to late sixties. Hopefully someone will be along with something more definitive for you. Member roughbarked may be along soon to help out. Be careful how you handle that movement around the balance wheel (Under your thumb.), as the balance has tiny pivots that can be hurt by minor false moves. I realize that these little movements are hard to handle no matter what. Just a word to the wise. Good luck.
There were/are a number of movements measured as 5.5 x 7'''. Though not a lot of manufacturers made movements this size.
Suggest you type 5.5 x 7''' in Dr Rafft's site search engine.
There are no Witttnauer's listed there nor Longines that fit the bill.
Not That Dr Ranfft has listed every movement that has been made.
Probably the most commonly used was the AS 976 though the plates on this don't exactly match.
Sometimes it's not at all easy to determine which movement a timepiece really has. Many brands suggest exclusivity with confusing proprietary names, even though the movements are often supplied by one of the usual suspects. Sometimes this is done merely to create the illusion of in-house movements, although in other cases it's more legitimate because the brands undertake their own modifications, add modules, or otherwise improve the movement.
Yes, roughbarked, I was looking for such a size, 5 x 7-8 ligne'ish. I didn't see anything near a perfect match. And I'm not sure I looked at that particular AS you mentioned. I looked at one made by Venus that was somewhat similar, but I didn't take as good of a look as I could have. I'll try later.
Perhaps a look at the wind/set parts would help. I don't know the OP's experience as far as getting to such things safely. That's a little 'un. Cheers.