Will a rpm air gap intake fit under the hood of a 1967 dart

Yes, with the Mopar Performance repop of the OEM early 340 air cleaner. Here's my 67 Barracuda with 360 and a 750 Holley.

View attachment 1715539607

Will also fit a 65 Barracuda 340. Same intake, same carb.

View attachment 1715539608

Drop base with three inch filter will give you even more room; probably could put a small spacer under the carb.
Love the clean look on that 65. Kudos