Going from memory -- and a rapidly fading one, it seems -- here...

Remove the #1/3/5 rocker stand Helicoils; some have come out easily for me, others have required "professional help".

Drill & tap those holes to the same depths as the threads for the #2 & 4 rocker stands, using 3/8-16 Helicoil inserts. I used .9+" inserts, but .75" are more commonly found.

Once you've figured out how much longer than stock all the studs need to be with whatever rocker setup you have, contact ARP directly for the correct size.

My experience was that the mail-order places don't show a full list of ARP sizes, and even ARP's online catalog is mess to try use to find them. Avoid the hassle and call them directly to talk with a sales rep.