Huh, this is fine mess.
I'm not the most knowledgeable here but I'd say those are E7 heads, and you've got the right plugs in the 25's. They should work ???
One a side note, those are not stock headers.
Someone will chime in and give you the right answer.
306 with all bolt ons, yada yada yada, letter cam, ported E7's, T5 swap, full exhaust, 3:55's, 2" drop, and the worst paint you'll ever see or feel.
Dyno'd 300/316, 2745lbs-track scale
Best ET………12.4@108, 1.66 60ft on 8" ET Drags.