I bought a pair of 12" Alignment Plates from Gil Smith Racing Fabrication and they did the job of measuring my steering ratio.
I had a couple cam degreeing wheels laying around from my bike motor building days which fortunately fit nicely on the turntable of the Plates
Like so many things, there are tricks to getting consistent info and i learned each trick the hard way.
Bottom line is my steering ratio is very close to 25:1
karl