I was reading the category rules... and it´s allowed small block cast iron blocks, maximum 420ci and transmission and heads are free of choice. Maximum deck height for the block 9.56". And can use up to 500hp nitrous shot single stage.

Diego can correct me but I think the chevy 6 cylinders use a lot of NITRO on this category... don't know best ETs.

Br,

1973 Brasilian Dart
E100, boosted 390"