I get anal and do that chit looking for a horse here and there.
In addition to the pocket porting and port matching and clearance around the intake valve, some things include:
Carb is milled and blended. Note that the "dead zone" at the interface of the air cleaner base and carb has been filled with a piece of rubber cable and sealed into place to smooth this transition. Also note the "nose cone" at the transition of the screw and post. There is actually a piece of heat shrink tubing that covers the treads from the wing nut (bottom of the air cleaner top) all the way down to the carb completely covering (and blending) the centerpost.
The intake itself has been internally "massaged" to get rid of the casting ridges as well as smooth out the divider and provide a smoother airflow. The 1/2" spacer is ported and blended to the manifold. Even more work was done after the pics were snapped.
When the manifold is installed, I lay it in place and using a stiff wire, I "feel" the transition and shift the manifold around to get this the smoothest. I then use a marker to mark this alignment so that after I do the gaskets and China wall, I can just lay it into the proper place without shifting it around.
I even do things like putting multiple coats of ceramic-bearing paint on the base of the air cleaner to reduce heat transfer.
When my block was prepared, it was actually clearanced for the intake valves. I don't see many do this anymore.
My combination makes ~350 crank hp and I get about 290-300 at the wheels:
331 CI, pump-friendly 9.5:1 CR
K&N 14"x4" air filter, Corvette drop base and lid
Holley 600 dp, choke horn milled and blended, Primary - 69, Secondary – 74, Squirters - 21
1/2" Aluminum open spacer port matched to manifold, exterior polished
Edelbrock Performer RPM intake manifold, port matched, exterior polished with all extraneous castings and lettering removed
Homemade lifter valley splash shield to keep hot oil off manifold bottom
Manifold heat riser crossover blocked
Camel hump 1.94/1.50 heads hogged out to 2.02/1.60, pocket ported, port matched, pump-friendly hardened seats, 3-angle valve job
Cylinder bores clearanced to unshroud the valves
Comp Cams 1.52:1 roller-tip rockers
Crane Cam Vintage Muscle 327/350 hp cam, 222 degrees @ 0.05, 0.447" lift (with 1.50 rockers)
Doug Thorley headers, dechromed and ceramic-coated
2.5" mandral-bent exhaust (including tips), 2" cross-over just before rear axle
DynoMax stainless Ultra Flow mufflers
Millerspeed 1-1/2” Gilmer under drive belt drive system
Mallory Hyfire IV CD ignition box triggered off Accel points
Mallory high voltage chrome coil
Mallory spiral-wound coil wire
Mallory solid copper plug wires, ends soldered to wires
37 degrees total ignition advance
Carter high volume fuel pump
Melling high volume oil pump
Polished aluminum high flow water pump
Flex fan with polished aluminum spacer
Polished aluminum one-wire 100 amp alternator
Header Power Bracket
Keisler TKO600 5-Speed
3.70:1 positraction with Big Block yokes
225/60/15 Firestone Firehawk SZ50s on 7”-wide Western 30-spoke Turbine Wheels