At nauseum..318 intake manifold to 340 or 360.

H22A4 said
Also consider adding a dual exhaust and recurving the distributor as it’s likely set up for a smog advance.

Did you even read what the OP wrote in his first post #1 ???

Spin'em75 said
Hey, everyone! New to this forum. Got my first Plymouth Duster a few days ago ('75) with a rebuilt 318. Dual flowmasters were recently installed (not sure on model)

He's already got that covered.

Tom