spark plug help

What plugs should I use in this setup:
340/416
eddy heads 65cc
eddy performer rpm
bg 650 mighty
10.5 to 1 cr
tti headers
535 hp at 5200
531 tq at 4200
904 with tf-2
This will be in a 72 dart swinger with a 8 3/4 with 3.23's
FBO ignition