Spark Plugs

I am going to change the plugs. I noticed that the early 340's used RN9Y. Now they list the plug as RN12Y which is hotter. I have the Edelbrock heads so I was using RC12YC. I was going to go with the Autolites which would be 3924. Do I get those or do I get 3923's. I am running 10.2 compression if that matters. Thanks for any help.

Fred B