Measure and call Smith Bros.
Set the adjuster to where you want it and don't be afraid to measure a couple and get an average.
The correct length pushrod is never a bad thing.
I don't see where you hang your spurs , but if you are anywhere near St. Paul , Mn. I have the correct measuring pushrod , a 5/16th steel ball and 12" caliper that I will watch you use and offer snide comments while you do it. LOL