I wanted to replace the accelerator rod setup on my 64 Econoline with a cable one so I built this very simple adapter to use the existing pedal assembly, since these photos I have changed the washer and spring setup to look a little neater but it works incredibly well.
I fitted a pair of Rivnuts to the front valence and bolted the bracket to them, the original pedal arm on the assembly rests on the bracket and I used a bolt to attach the cable end and spring to the original assembly arm.
This is the bracket, its very simple but effective!
Cable detail from above:
Spring detail from above:
Bracket attachment to Valence: