Can I put a smog intake on an older block? '75 intake with those weird smog rail things on either side. I was planning on getting a TA dual plane intake in the future, I'd be fine just using the 750. There's nothing wrong with it, just needs rebuilt. As my 800 would. I bought it on a whim about a month before I found the 350.
The '75 intake shouldn't have any A.I.R pump passages in the intake, IIRC, 1974 was the last year for that.
The intake (smog one) has the runners on both sides built into the intake that are capped off on both sides with plugs. '70 intake doesn't have those. My '76 two barrel intake doesn't either.