Hello i´ve honored this watch and don´t know which model it is, so that i can calculate for how much i can sell it. i think it is from the 60´s (SN)
your watch is a classical IWC Automatic with a Pie Pan dial, The movement is a Calibre 8531 and was made in 1961. The condition of case movement and dial are below average. A Service would be highly recomendable.
The Forum etiquette doesn't allow to discuss monetary values.
If you take the weight of the 18ct case and braelet you can evaluate the value of the material.