For the rocker shaft stud kit use Trick Flow Part number 61600613 or you can piece it together with ARP individual studs AJ2500-1B and ARP nuts 300-8332 which is a 10 nut package.
I had to use 2.750 long studs on my Trick Flow heads since I was using the HD style shaft hold downs. The 2.500 long studs might work with a stock stamped hold down?