Is it OK to use 3/4 thread length in a 400

It was recommended to me to use a 3/4 length thread plug in my new 400-470 stroker 11:1 comp and stealth heads. The recommender did not respond when I mentioned back to him the motor before rebuild came to me with 2 pistons having golf ball size hole in them. I wasn't questioning his knowledge but when an answer has ( I think) in it it makes me concerned. Soooo any and all imput on this appriciated. Thanks