305 14014416 heads

[68metal]

Please tell me what's the correct spark plug for a SBC 350 with 305 heads.
Casting # 14014416. has a mild cam, roller rockers 680 cfm Quickfuel carb.

thanks in advance
68 Chevy C10

[MonzaRacer]

Cold plugs start at R42ts and run up to hotter plugs R45ts. My personal preference is CR43TS, or the Rapidfire version AC1, AC2 will be hotter version
R42TS. - 41-809. - CR42TS
R43TS - 41-817 - AC1
CR43TS. - CR44TS. - AC1
R44TS - 41-803 - AC2
R45TS - 41-905 - AC2 - CR45TS