R12 How to buy in one UOM and Ship in another UOM (Conversions)

Hello :

One company buys bottles of wine and they sell them in Cases of 12 Bottles.

As far as I know I need to setup one ítem.

Unit of Measure

Primary =Each

Tracking =Secondary and Primary

Pricing = Secondary

Secondary = Case of 12

setup>unit of measure>Conversion

inter-class

W42059A=Box

class =package

Conversión = 12

Now I add the ítem in the Price List

I need to raise a Sale Order and assign the ítem W42059A but I need to Ship 1 Box of 12 Bottles.

Please Advise