I think my 727 is fried. Now I'm at a crossroads...

Please forgive me, but what do you guys think is wrong about the plugs? I have iron heads, and all the searching I've done has come up with short reach plugs like the Autolite 85, NGK XR5, and Champion RJ12YC plugs. From what I understand, if I went with aluminum heads, that's where I may need to switch to a longer reach plug. Am I mistaken?
What year and what engine is it? More to the point, what HEADS?