Need help in authenticating a 50’s-60’s iwc

I’m completely new to Iwc, and I am looking to purchase this piece. What currently throws me off are the following:

1) the three digit number on the movement ring is misaligned

2) caseback - on the the iwc logo’s “scafusia”, the second “s” doesn’t seem to have been engraved evenly. So is the “Swiss”.

3) the cal 89 movement does not have Geneva striping (although I have seen a few without it)

Also I have no idea on how to authenticate the dial.
Thank you!

Hard to see the case condition from those photos but looks fairly corroded.

Dial looks correct to me, same with the hands.

For some reason a lot of the cal 88s and 89s I’ve seen have survived in very good condition - this one isn’t as clean as others (again, hard to see the case). Would come down to a very good price and additional photos.

Looks authentic to me and no parts outwardly scream counterfeit. Condition of components all around appear to match each other.