Blown bb chevy spark plugs
 

hi I have a 34 ford coupe here in the uk running a blown 502 bb chevy, I checked the spark plugs and its fitted with ngk7fs plugs, I checked these to a tecumsa lawn mower engine !!!!!! can anyone tell me what plug I need using ngk, im told I need copper core plugs and what gap size, Im not Drag Racing just Occassional Street Race. Thanks