What head bolt kit to use?

J. Cower said
1971 340 block and using 78 360 heads. I see two kits from ARP for small blocks and some have two size bolts and some have three. How do I tell which kind I need? Probably dumb question but it's my first build.

Should be 3 different lengths for those heads. I think the Edlebrock heads have a slightly different length.