help deciphering these numbers. what model? value?

Hello all, still early in the learning process here. I posted previously looking to verify this watches authenticity... thank you for all the great info on that.

I'm still trying to do research. I managed to grab a couple shots of the inside with the reference number. I went to some online number lookup sites and I couldn't figure out a model with the numbers shown on the inside of the watch. The number on the movement (21823208) shows that it was from 1964 on one website. The case numbers show ... 5958170 and LL6590-1 ... can anything be learned from these?

Any idea how much this watch might be worth? I can't find a similar watch anywhere. It is working and has kept time for 24hrs so far. I think I'd like to have it cleaned up and serviced, (if it's worth the cost of a service) any trusted shops in the U.S. Midwest?

thanks for any advice or info.

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Thank you, that is very helpful info. I found some threads about the Ross watch cases.