The best way to be sure is to buy the adjustable one and measure. Stock length may work, I was told it would on my application but there is slight play in mine after taking the valve lash out. I should have measured to begin with.
2014 Sterling Gray Base 3.7 3 pedal FP6 Package - stock
1967 Coupe 306 roller block, E303 cam, C4 Auto, CSRP Power discs