Upgraded 273 commando intake manifold suggestion

Well Hp is found in the higher rpms. The D4B for LD4B have potential for more hp. May cost some torque on the street - the Hot Rod Magazine dyno test from '68[?] hints at that. Other thing to watch with the dual planes is hood clearance.
Spacer to make a larger plenum should help on the higher rpms with a stock single plane intake.
Years ago David Vizzard tested a bunch of aftermarket intakes and found that many did not have as good fuel distribution or general performance as the factory intake. I'm sure he wasn't testing a 273 but it does serve as a cautionary tale.