I just got off the phone with Ron Johnson, the guy that built/ owns Ivo's "Barnstormer, Herbert/Shubert SBC TF, and the Greeks "Chizler". This year Ron and his daughter are going to help organize the Cackle cars at the Reunions, to help Steve Gibbs with all he does at the reunions. I called him to get the guideline on cackle cars. The guidelines are on-line at Cacklefest.com.
It is not recommended to use steel rods, matter-a-fact they are working on motor guidelines and will post them when they are done. What your goal should be is build a race motor, with some mods to keep it from blowing up, and hurting crew or spectators . What Ron is doing now and suggesting is alum rods, NO head gasket O rings and even OEM head bolts, so you have a safety valve to let the fluid [ nitro] out with out blowing the side of block out.
Another thing to keep in mind they will not allow a period correct car that was never raced. If you can get pictures and a Family OK to build a car that did race in the 60's and early 70's, then build away. The reason for some of these guidelines is some motor have broke and even sent parts into the stands on push starts, and the cars invited need to be restored race cars because it was getting out of hand. One year at the Reunion at Bakersfield they had over 100 cars, talk about a cluster, and traffic issues.
So check-out the the cacklefest site for guidelines and have fun !
Jon Hansen, Hayden Wheels