I should be changing over my heads in the near future, but I am not sure what to run. the new heads are cast iron Bowtie Heads cast # 14011034. Should have a total of around 9.6:1. I really don't know where to begin on picking a plug.

You need to run a 5/8 hex, 3/8 reach tappered seal

I have the same heads on a 406 SB with 9.6:1
I use a AC-Delco R44t(short end), you can run a R44TS to start, then figure out if you need to run cooler or hoter plug. The TS has a longer end

Mint. Thanks :)