Authentication Help Please?

Hello.  I'm new to the forum - just found it today.  What a great resource!  I'm hoping to buy a vintage IWC wristwatch but am pretty concerned about authenication.  I own several luxury watches - Rolex, JLC, Omega; but, this will be my first IWC.   Can someone please give me an opinion on whether the watch in these photos appears to be genuine?  Thanks in advance!

It’s a real IWC Cal 403 from early 70s

I'm sorry - I forgot to post a picture of the case :)

Wow!  Thank you so much for the quick response!! :)  Hopefully I will end up with it :)

Hello all!
I'm unable to star a new topic, so I put the question here.
I want to buy a vintage IWC wristwatch Cal C83, but am pretty concerned about  case authenication.  
These are the only pictures I have. Price request was ~800 eur. Is it a fair price?

Best regards,
a

Looks fine 

The condition of the watch is fair.....
Looks like the caseback has been aggressively scrubbed with steelwool for some reason. 
If you have any doubt at all, Walk away.