If a plug is too hot then all you need to do is change it to a colder plug in the same family. Been a long time and I'm sure someone will correct me if I've got it backwards, but most domestic type plugs it means subtracting a number from it to get a colder plug. Autolite 66 would be a 65 colder. NGK it is the other way around from what I remember. If you get, for example a BPR5ES plug and need a colder one you would want a BPR6ES. I'm just using a number I remember and not a MOPAR related number. Just an example for you.
You need to have your mix and timing set right to really know where you are on heat range and then start adjusting if needed.