Do you have the short leads and female bullets at the firewall from the bulkhead connector?
If yes then measure the length extension you need and search for that. They are out there and have male bullets on one end and female bullets the other. AMS obsololete comes to mind and others. Or make your own from black 18awg with standard male/female bullets from any parts store. To make them look more authentic remove the plastic cover and put a layer or four of some black heat shrink tube to cover the crimp connector to about 1” length.
