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More than likely it was used on a small displacement, high RPM, extremely efficient engine. 360 cubic inches or less. Bigger is not always better... Not to bash the OP, but I would take the top port over the bottom one any day of the week, chances are it is a very highly efficient, high velocity port with every aspect of it set up for a max effort combination. The short side radius is a lot bigger than the bottom port for sure. The bore size wouldn't be as critical with that port it as long as it was 4" or more. 
The short turn starts at about the same distance from the deck and without looking at the chamber side of the head it would be fairly safe to assume they end in roughly the same place as well, the differance is in port height and width. The only time the samller port head will make more power than the bigger port head is if everything else is too small for the engine like cam, intake, exhaust...
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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