Pick the one that feels better when you sit on it or looks better to you. They are basicly the same bike. They have a few cosmetic differences and the Speedmaster has dual front discs. The riding position is different too Speedmaster is more aggressive and the America more a relaxed cruiser. It isn't hard to make one into the other so look at what you want and how much it would cost to make each into what you want in the end and go with the one that is easier and cheaper to tweek into your bike.

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