[johnneilson]

Jay,

The original Cragar head was a conversion done to increase capacity of the AA trucks, it was a true bolt on conversion.
You are now asking about performance gains and modifications, a much different question.

Jim Brierley has a book out, 4-Bangers and Me! Not too expensive and gives a really good basic understanding of the modifications done over the years.

Back to your question about carbs and manifolds, it depends on your application and intended usage. I prefer a single carb on a street car, Holley 94/2100 or a Stromberg 97.

Best, John