Cam for stock 318

YOU MUST REPLACE THE LIFTERS WITH A NEW CAM SHAFT, PERIOD!

Further more, I make these suggestions and without knowing your gear ratio and tire size. I'll assume a converter change is not going to happen, so with that in mind, I seriously suggest saving your money for a cam and lifter set along with the matching valve springs for this cam, the largest suggest for a stock converter by Crane.
(But I do like Rocco's cam. It will just need a gears @ a converter for a good result Mello sound.)

Crane Cams;
Advertised duration/ 272-284
The duration @.050/ 216-228
Lift w/1.5 rocker - .454-.484
On a 112 which has a smoother idle than most cams ground on a 110.
This cam doesn't need a torque converter change. I do suggest a min. Gear of 3.21/3.23's with a stock tire for a good result. Do not go above a 3.91 ratio, use wider tires at a max of 26 - 26-1/2 inches with the 3.91's. You'll like a wider tire with the 3.21/3.23's.

Cam and lifters should be treated as a matches pair for each other. The springs will be needed since the stockers are not up to par for this or any cam change IMO.

Comp Cams has a similar cam (or 2) on a 110 for that Muscle car sound.

Don't cheap out, do it right and do it once as a package and feel the bang for the buck all at once. You all ready have the carb and intake. Adding this will help out nicely. Dual exhaust would also be nice, headers or not.