What is the best thing to do for a throttle cable on a vortec conversion into a '72 FJ 40?

Lokar makes one that's easy to adapt. you can find them at streetrod shops.

I concur with Mike....those Lokar cables are the shiznit:D

Lokar cables may well be the shiznit, but I am a cheap S.O.B. so I used the OEM Vortec cable and modified an early LC throttle pedal (such as a '72) to fit the cable end. It has worked well for me.