Two of my jacket conversions had slash pockets that had flaps and openings parallel to the bottom hem. On one, the flap was removed and simply moved up a little, thus allowing use of the pocket. On the other we used fabric left over from the part trimmed from the bottom edge to form a new slightly larger flap.

Patch pockets seem to be preferred only because they are easier to modify.

I have two jackets now at my tailor being converted. One is a simple two button blue sport jacket and the other is a black corduroy. The blue one has slash pockets and the corduroy has patch.

Also remember that the left over fabric can be used to form cuff flaps and epaulets, if you want. Buttons can also be changed to complete the look.

It’s the cheapest way to go, that’s for sure. And if you or your tailor are good at sewing, the end results are very good looking.