LA intake magnum head questions

Iv have been studying this subject for a wile. I have two questions.
1) can I drill the LA intake instead of the magnum heads? If not then--->
Question 2) how deep do I need to drill the heads? 3/8" 1/2" 5/8"?
I can't find much info on question #1. But have read its been done
Thanks in advanced.