I know man but figured i'd post it anyways incase you were one of those guys with $$ coming out of your ass and like to be able to pay the money for what you need instead of making a few trips to the hardware store
The air injection holes on e7's are 5/8 coarse- not sure if they'll be the same with your 351 heads. I used all-thread and welded a nut to it and screwed it right in - cost all of $2 from home depot.