Hi Paulza, Welcome to the forum! I haven't been around much myself, but just your luck! I'm here today!!
It looks like an old Portuguese from before the 70's. But be aware, watchmakers have been fitting different IWC Calibers, since the originals where hard to maintain.
After a while watchmakers fitted cheaper, smaller calibers and so it started to happen that way smaller square IWC calibers (designed for square IWC female watches) where put in these types of watches, dramatically decreasing the value of these things.
really hard to tell if this is the case with this watch... might have something to do with only 1 photo.
Anyhow, if you have 1800 to spend on a vintage IWC, i would rather pick an other one. There are classic's out there that keep their value, and will increase!
If you have only seen this model and just want an IWC, so you can say that you have an IWC.... Go get em tiger!
Cheers!
Frank