I understand you can run the 915 heads if you use the 1.60 exhaust valve. These are way better than 516. To ID them in junkyard look on front machined area behind Alternator and if stamped HP they are 1.75 ..... if not stamped 1.60. If you can run 67-69 Intake for 440 (178) which I don't know.. It is also way better. I have several of each.
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