1969 390 build

I am reading threads about 502 heads.I am new to BULLTEAR and never heard of these heads,would someone explane to me the difference between 401 heads and 501 heads.I have been getting information on this 390 engine for two years between three back operations.The threads I am reading are very knowledgable to me.It seems to me that I am less than a novice to all of you.This engine I am trying to build will be a street/strip engine not a daily driver.What I would like is a engine with 500+hp and stay together firmly.If anyone would help me out I would greatly appreciate it.I have read the article in car craft.Is that the best that there is?
Thank you.
Rich.

A 3226502 head is simply a head used in all 401 74-78 and 4bbl 360s 74-78. It is a thick casting that takes porting very well.

Thanks for educating me on the 502 heads.I think This engine will take me quite awhile to build.But I will enjoy every minute of it.
Thank you.
Rich.