The OEM cast iron '67-72 intakes flow well, and if building the 550 ft lb/near 500 HP+ Pontiac, SD Performance has a CNC program that closely follows the prep work Cliff Rugles performed on his cast iron intake to make it flow extremely well on numerous ported KRE and Edelbrock head 455--474 combo's . If looking for a '67-72 4bbl cast iron intake, the '71 models have consistently been the cheapest to pick up for at least the last 15 years. For the money, one can buy a $50-75 '71 intake, have it shipped SD for the CNC work, then when get it home, separate the water crossover and with a sawsall and a hammer and angle grinder eliminate the heat cross over. End up with a 20 lb cast iron intake that (1) fits, flows better than an RPM, and costs less than the JoParts junk repro RA intake and having it CNCed ported and fixed.
The Performer RPM intake is a 1.25" taller on one end of the carb mounting pad, that nearly always creates hood clearance issues. I've installed the RPMs on a few Abodys and they typically require an extreme drop base aircleaner to get them to fit under the hood....that means no factory RA pan . The repro JoeParts RA IV-455HO intake has port alignment issues. You can email Dave at SD Performance and ask him about the work it takes with the repro RA intake manifold to get the ports to line up well with ported iron heads and aftermarket the heads. I will post a link with pics later tonight.
The edelbrock 1406's , et all, are Carter clones, and would require an adaptor or a square bore intake, and not near as good a choice as a moderately prepped Quadrajet. the Carter clones also have different aircleaner base circle. Cliff Ruggles Qjet book is a great value, and will help immensely in setting up a relatively expensive Quadrajet core. Cliff is a huge fan of the '77-80 Buick and Pontiac 800 cfm . They are relatively cheap as good cores and have numerous refinements over the earlier '71-73 Buick 800 cfm Qjets (one of my longtime favorites) and all of the '67-72 divorced choke Pontiac Qjets, of which quite a few are VERY expensive as quality cores.
