Is this the right size for my window?

Sounds like you're looking to install operating hardware on a new application. This isn't as easy as it sounds. That said, I think the 39-069 is too wide for your opening. You might be better off with the 39-069 so you will have some play when the arms are fully closed. You will also need to install the 39-170 bracket on the window sash vent. That said, if this is a new application there is no guarantee that this hardware will work.