alternative kickdown linkage?

Don, for the 68 Barracuda I looked at the cheaper eBay kick down cables but decided to go with the actual Lokar cable kit. It was easy to adapt to the GM Vortec TB that I am running and came with the correct adapters for the 904 transmission. Easy to adjust and functions fine.
Good to know.
And on the vehicles in question a manual valve body is out of the question, though I can see what you mean, "if I did so"