What spark plugs for 291 Hemi?

I actually posted this question on a thread about plugs for a 331 hemi and didn't see an answer.

I recently aquired a '55 Desoto with a 291 hemi and was wondering what size spark plugs you hemi "gurus" recommended. I don't want to ***ume that the same size plugs that fit the 331 will fit my 291!

Thanks in advance for any help!

Also, where do I go for plug wires, dist. cap, rotor, points? Can this stuff be bought at auto parts stores? (Thinking not!)

 

try this
http://www.rockauto.com/catalog/raframecatalog.php?a=G-Champion
hope it helps

 

What year 331?