Header brain fart

Hey ya'll, I picked up a set of Doug's 453's for my 74 Duster with a 360 and 727 from Summit. Before I bought them I looked and read the 453's were the way to go. I SWEAR I read the Doug's 453s were the ones I need. Box finally showed up today and as I was looking at the paperwork I noticed it omitted my year (74) from the application year. Checked Doug's website, and nothing for the 74 Duster. Summit's website says it doesn't fit.
Did I **** the bed on getting the correct headers? I am sorry to ask ANOTHER header question but, I figured if any group of people could get me the straight answer in a timely manner it was FABO.


Thanks