I called my local NAPA store and they show this head requiring a washer type plug. I will check down inside of the socket relief to see if there is any signs of leakage (black trails) around the plugs. If not, then I will put my existing plugs back in.
I do have some old Autolites that I used to use and I will check against my existing NGK's for any size differences.

Thanks again to all.