Jim, in the case of the Dodge D500 engines they were all Hemi's until the introduction of the "B" (wedge) engines in 1958. As such chances are that it would have been a dual point.

As the distributors would interchange between the Hemi's that had a Poly counterpart who knows how much swapping occurred.

Believe me I don't know everything about these engines (hell there were 12 different displacements divided between Chrysler, Desoto and Dodge with all three having versions in both tall and short decks) and nothing was written in stone with Ma Mopar.

Don Jr as far as I know all the first Gen Hemi's had the studs for the wire covers. It was/is pretty popular to have these removed to eliminate the covers and use 426 style dust covers (it's a mod I had done on the pair that’s on the 331 that will be going in my 37). I suspect if you look real close you will find the places the studs were spot welded.

I like the observation Don made about the size of the Hemi Block after you got the heads off....... it's almost a let down isn't it? It's really a testament to the original design and quality that they were able to make them go so fast with what is by todays standards would be considered minimal prep work.