Recently finished building a 383 and need some advice on what plug to run

I'm running about 10:5:1 compression with a set of PBM strike force heads, with a factory ignition other then a msd coil and plug wires.

I usually prefer ngk and figure around a 4-5 for heat but what about the rest of the part number?>

 

You want the coldest plug possible that doesn't foul up. Best plug temperature depends on a lot of factors. The only way to know which temperature range you need for your particular selection of components and settings is to try a set and read the heat line on the ground strap. Too hot a plug and the tip melts. Too cold a plug and it fouls up.

Spark plugs are cheap. For a daily driver type engine, start with some ACdelco R44TS. If they foul up, go to a R45TS

With the NGK race plugs in my engine, NGK's temperature numbers go up with a colder plug. ACdelco's go down with colder plugs.