Im having a hard time figuring out what specific spark plug to run on my Firebird

I am confused about heat ranges, and i figure some of you would probably know.

Specs:
Chevy 357, 10.65:1 Compression, 520/544 lift cam 310 duration, 2.02/1.60 Procompelectronics heads 64cc. Stock rods & crank

What the cyl head company says:
Spark Plugs
All Procomp 23deg. SBC heads use standard 14mm. x 750' reach, 5/8 hex, gasket seat sparkplugs like NGK R5671A-7, Autolite 3924, Champion RC12YC, etc.
Remember that higher compression/ boost require a colder heat range sparkplug.

Any ideas guys?

 

AC/Delco R43TS

 

I've been looking into this lately. I found that AC Delco offers 3 plugs that are 14mm .750 reach 5/8 hex. c43ts, c44ts and c45ts. R= resistor plug 4= 14mm thread 3,4,5 =heat range TS= Tapered seat. Cold engines (low compression) need hot plugs and Hot engines (high compression) need cold plugs. If you want to stay with AC Delco, go with the c45ts. Its the coldest plug you can get in that brand at Autozone, O'Rileys, ect.

http://aftermarket.federalmogul.com/...ce%20Chart.pdf