String recommendation for old Silvertone parlor

Just bought an old '60's-ish Silvertone (Harmony??) parlor acoustic-not here yet but looks to be in OK shape.

It obviously wasn't an expensive guitar to start with, and now it's old to boot. The neck joint is solid and tight, but I see no sense in straining things.

Could anyone offer opinions on what strings or guage they would use?

Would tuning down a little help any?

well.. I reckon that the strings that would have been used on it back when it was new
would have been flatwounds, and prob'ly of a heavier gauge?

10s should be alright, no need to use flatwounds unless you prefer 'em.

tuning depends on your tastes and/or needs - open D is nice for slide, but as far as
putting strain on the neck I don't think you're in any danger.

This is my recomdation for that size and typ of guitar..
http://www.musiciansfriend.com/product/DAddario-EJ16-Phosphor-Bronze-Light-Acoustic-Guitar-Strings?sku=100182

I have 10-47s one mine ... I guess she can withstand the pressure of 11-49

Here a pic of mine, is yours like that ?