Use the pin for the hinges you have. Most have a smaller pin for the horizontal side hinges, larger diameter for aft cowl to fuselage hinge. The top cowl pin can is the smaller (but uses larger hinge) so the pin can make the bend. I use the larger pin and just reduce the diameter for the first 10” or so of the pin to make the bend. This removes some of the slop in the top center of the cowl.
Van’s will sell you the pins. The smaller pins will be in a coil (easy to ship), larger diameter pins will be sent in a PVC tube: https://store.vansaircraft.com/catal...list_mode=grid
ACS is about the same: https://www.aircraftspruce.com/catal...03-49000-3.php
No matter what, every cowl pin must have a retaining mechanism. Recommend you add these when you do this maintenance. No pin can be allowed to “migrate”.
There are good but easy ways to achieve this, as well harder and not as good.