I estimate at 60 mph I have 20 degrees of loose steering. There is no play or linkage problems. I am very familiar with that on my older 65. But this travel is smooth and not the quick response like my modern 91 ford tempo.
This question was posted on the VMF and this was my reply that I would like to share.
I would suspect the alignment settings. Do you know what the current settings are? Was the car aligned to factory settings? A performance alignment will usually help with high speed stability.
Opentracker Racing has a roller idler arm solution for your issues with high speed steering.