Selling Items with P or M Stocking Type


I am looking for recommendations or feedback on the stocking type to use in the following scenarios and question:

1. Stocking Types
a. A purchased item with a stocking type P that is then sold.
b. A manufactured item with a stocking type M that is then sold.

Is it good practice to sell an item with a P or M stocking type? Is there any reason for/against converting it to an S stocking type item first?

2. If it should be converted to an S stocking type first, what would be the best way to achieve this in the Inventory module? We currently do not have the Manufacturing module, I am looking for a straight-forward work-around.

Thank you.