Was any work done on the intake to improve the flow? Those old 2-plane Edelbrock intakes are capable of making some prodigious amounts of power, especially if you do some deep porting on them.

I have one on my 493" wedge with the mechanical secondary carbs making 715 hp at 5500 rpm. It was deep ported by Hughes Engines, and is bolted to a set of Hughes Stage 2 ported small port Indy EZ's. I'm running a smallish hydraulic roller.

The wide band was indispensible as far as dialing in the jetting and squirters. I found no need for a chassis dyno and dialed it in on the street using the data logging feature. It makes it pretty easy to do. My hat is off to the guys who dialed them in by the seat of their pants and reading the plugs. Now, that takes some skill!