I made my own when I put the mini-starter on my '64 Polara. I did not use FireSleeve on the starter cable, but that is an option. I did use it on the 727 shifter cable in the race car and on the push button cable in the '64 to protect those from header heat.

It is easy to make positive and negative cables that are superior to NOS, after all they are made as cheaply as they can get away with.