Spark Plug question

[1970Duster]

Ok normally I'd run Bosch Plat 4 plugs in my motor, however after talking to my engine builder those might be to high of a temp. I have Edelrock RPM Heads 60779 (closed chambered) 63cc, Stock length Stroke and stock length rods, Flat top pistons (Forged Alum +.030 over), Total seal gapless piston rings,MSD e-curve dizzy and MSD wires 32749, Cam has been degreed (Roller Cam) specs are:
282in/290 out AD
at .50 231 in/239 out
.535" in/.550" out Lift
110 in/106 out Lobe
Range is 2400-6200 RPM
requires 2500 stall (3.42 gearing or better)

Anyway Edelbrock reccomends Champion Spark Plugs E71-1 (RC12YC)
Question do these seem like to high a heat range for the motor?
Any thoughts on these plugs or possibly these NGK Spark Plugs 7938 (BKR5E)?
Any help would be great :salut:

 

[1970Duster]

Oh yeah forgot to mention it has 10.5 to 1 compression

 

[69DARTS]

ngk plugs

 

[1970Duster]

ngk plugs

Ok I'll go get some! You wouldn't happen to know if these run hotter or colder then the champs do you?

 

[green1]

Go on line; 4secondsflat.com. Shows how to read your plugs.