Do you realize that with 3.21 gears, 26" tires, and an A904, your WOT mph is gonna be ~50 mph in First gear, and 84 in Second, both at 5500rpm@10% slip..
So, on the way to the speed limit, yur only gonna hit the powerpeak once.
And
On the 1-2 shift, the Rpm is gonna drop from 5500 to around 3250, which is waay off a 340 cam. which is not gonna wake up until IDK maybe 4000@ 60mph. Which means that from 50 to 60, your reduced-pressure-318 is gonna be a lil all talk/no action.
Almost everybody here will tell you that you won't notice it, but they're wrong. I mean the 340 cam will drop your cylinder pressure about 20psi, This will be most noticeable below 3000 rpm, but the softness carries right on up until the engine hits Peak-Efficiency and the power increase will pale in comparison to your expectations. So the reason you don't notice it because it is all soft, just less soft at rpm.
I mean everyone here will tell you that an 8/1 360-4v with a 340 cam, in 1974 DartSport, was a sucked out slug.
But those same people will tend to pump up the reputation of an 8/1 318-4v with the same cam, giving it glowing reports.
I swear there is no pleasing some of these clowns.
Do yourself a favor; the stock cam that is in your 67spec engine, is the right cam for those 3.21 gears. If you need a lil more oomph on take-off, just get a higher-stall convertor; at least a 2800, more if it's a city-only car.
And for the love of all that is good, do NOT install a factory 340 cam or any cam with a 114 LSA, which is nothing but a pressure bleeder to a 318.
End rant