Autolight copper. I won't say that all the platinum stuff is a "gimmick" as they do have their place but the copper core plugs seem to be their best in our 5 ohs.
copper conducts much better than plat. plat is great for motors which have inaccessable plugs. but copper, since it conducts better, will suffer gap erosion faster.
also, remember that juice takes the path of least resistance - you can have 15 ground straps, but the ground path will be the one of least resistance (generally the closest one).
some guys say plats are alright in 302 EFI's. others have low idle issues and cutting out at 4K rpm.
Autolite (Or Motorcraft...Same Plug) Copper plug's all the way.... Nothing else.
Those Bosch +4 and +2 plugs are nothing but a gimik and a waste of money....the same goes for splitfire's, NGK V Groove's, etc. etc. etc.