[Walt Fricke]

Thread longer, and cut off some of the original threaded cable end at the clevis. If you don't cut off some, you can't shorten more than you can anyway, as the end will poke into the short lever arm.

There have been at least four external clutch release arms back under the bell housing, but the three which took cables with three threaded ends used cables of rather different lengths depending on the arm and system. From ~1977 until the G50, however, the clutch end wasn't a threaded rod - it had a swedged on sort of cast or forged loop end, to attach to the harp spring release lever system used on the car in question, and those only come in one length.