What spark plugs for edelbrock performer heads. 10.7:1 compression, TTI headers, 654 hp. street/strip. Thanks.

I use NGK 6987 for all my pump gas builds. It is an OEM plug so the price is reasonable. Should be fairly easy to find.

Been a few years since I had Eddys, but don't they use the same plug architecture (size/thread/reach) as 340 & Hemi ?

Not sure on that. I am not around my car, but I thing I have a NGK racing plug with heat range around 7.

the edelbrock heads use a 5/8" hex, 3/4" reach plug. I've been using autolite 3923, 3924, or 3926; depending on what i'm doing. i'm sure an NGK equivalent would work well.

I ran 8's at 12.1 comp and it ran well then I tried 7's and runs even better so I'd say a #6 will be real close at your comp.....

Champion RC9YC, Auotlite 3923 or 3924
I've no idea on current NGK #s

Being Alumium heads do you all think you should start with a standard heat of go colder? I was told to run a 5/8 version of the RN12YC but I want Iridum so I went for Denso IQ16TT's that are in the heat range of 12. They have a colder IQ20TT too that is a 9 to10 heat range

The reason I ask is I have never run aluminum heads on anything except my 2.2's. Someone told me that if the Iron head required a RN12YC that the alumumn would wick too much heat out of that plug so 1 or 2 steps hotter is needed.
1984 Dodge Shelby 2.2 10:1 CR was RN12YC. Mine was a 0.040 over true 11.2:1 CR and I found a RN9YC worked best.
1984 Dodge Rampage 2.2 8.5:1 CR was RN14YC