Is this Django (1966) 77 x 55 Four Foglio legit?

Roccot

Hi there! 

I'm new here and looking for a little help. Just scored this massive 4 Foglio Django poster from a seller on eBay. 

Can anyone tell me if it's authentic from the time of release? How am I able to tell?

New to this! So any information helps!

Best,

Rocco