Yes, Olds have three deck heights which affects the manifold width. 303/324, early 371, and late 371/394. So intake interchangeable between 303 and 324.
Yes, the deck height is the same but be careful, the 303's had small ports so when you try to use a 303 manifold on a 324 they will not seal at the top. I just welded up and machined the runners on an early Edmunds 2 x 2 so I could raise the ports to fit a 324 with #10 heads.
The Jalopy Journal
