Your 289 is going to be running about 7000 rpm to get the 350 hp that you are looking for so unshrouding the valves is worth some work. You will want to radius the valve pockets on the intakes but the Aussy heads are much better than the heads that we have here in the States.

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Paul
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retired mechanic after 35 years
specialized in Holley carbs and Ford Automatic Transmissions