Mostly stock 340 engine what Spark plugs

My 1970 340 with X-heads. Original bore,280 mega cam,600 Holley and stock cast mani's dual exhaust.. Who would like to take a crack at which plugs for this setup. Is a 4 speed car with 3.23 posi. Have had the car one summer and have done some improvements. Just a fresh tune-up left. Any thoughts much appreciated.