I believe that many people who under carbed them did so because of the Edelbrock recommendation also. I have an email from a tech guy who's been with Edelbrock for 30 some years and told me which carbs were recommended. See below:
Congratulations on having an intake manifold that has never been used and is at minimum 45+ years old.
Back in the day, when this intake manifold was new Edelbrock suggested to use 2-600 or 2-650 cfm Carburetors.
The RPM Range of the STR-12 S/B Chrysler is 3,500-6,500 RPM range, as determined by the Edelbrock Equipment Co. back in the day when they were new.
Sorry to inform you that even after my attempt to look for old literature I came up empty. I have Copied & Pasted the General Installation Instructions for the S/B Chrysler.
This will at least show you the intake manifold torque sequence for you to install this new intake manifold. If I do come across any of the old literature I will get a hold of you.
Sincerely,
Smitty Smith
Technical Sales Coordinator
