Add hotter cam or Add hotter head ?

Cam

With the increased duration moving the RPM up closer to where you want it to compliment the rear gear and tire combo, the increased torque made will accelerate the car quicker off the line and down the track.

As cast, the stock heads are not taxed for there airflow.

The increased lift is also a plus even though everything remains stock. The OE heads valve job is not even really fully used with the stock cam. Maybe if the cam goes past .400 lift but I don’t remember all the OE 318 cam lifts. The valve job is most responsible for lifts to .400.

Going higher in lift actually uses the bowl area. In order to see the gain on paper you’ll need to research stock 318 head flow & take note of how it flows past .400. But here is where “More the Merry” comes into play.

Using stock head valve sizes, the math says a LSA of 107.67.
An off the shelf cam that has this “107” number is a Thumper by Comp. You can go 1 degree ether way and be hard pressed to see a difference worth mentioning.

Many years back the ‘79 - 318 (7.8-1 ratio measured) I fooled around with was in a ‘74 Duster w/a 904 & 3.21 gears on stock tires did make it into the 14’s while being seriously challenged by the stock tires, stock distributor and the OOTB untuned carb.

The cam was a Crane on a super wide LSA of 112 and the following spec’s.

216/228 - .480/.484

A move to a better cam and wider tires never came around.