Offy intakes are hard to find because nobody uses them for years. They were obsolete in the '70s.
IMO, the best intake for your purpose would be Edelbrock "Performer". One thing not comonly known is Edelbrock wears engines out testing. Most other manifold makers (not high-end) simply make their intakes LOOK like Edelbrocks. No substitute for the real thing! Edelbrock isn't a 'buzz word", it's the BEST.