I bought the adjustable pushrod, but like i said the stock rockers pivot and don't roll so you can't get a clear measurement. Atleast this is what i think. I'm in the middle of redoing everything and will try that method but i doubt it will work. It would be nice to for sure know though before i rip up a lifter to convert it to a solid one.
i'm running the same combo gt40p with upgraded springs, 1.7 rockers, GT40p and explorer intake...runs great but doesn't have the sound/lope i expected. I wish i had went f-303. I didn't have to change pushrods..stock ones worked great.
I have the P-heads and a Stage 1 cam,and the stock length push rods are fine.My heads were not milled when I had the porting and valve job done (and yes,I installed Trick Flow springs as well).The cam is somewhat lopey as well,and the car runs really strong....seems to love the higher rpms a lot.