So you bought your way into the club!
Good Job. The bikes are fun, I love mine. I think the stock R1 spring would be way to soft for my set up. The reason I say that is that the spring I am running works really good and it is a lot stronger than the stock R1 spring. I did try the stock R1 spring with the stock swingarm, way to soft. Never ran it with the longer swingarm, but that would only be worse.
JDrocks helped me source my spring, check post # 958 of JDrocks build thread, I am using the same spring. This spring was pretty expensive, I heard some guys are having good luck with a Yamaha cruiser spring, check the Versys thread. I am running it on the lowest preload setting and I weigh 170 lbs.
How is the riding in Arizona this time of year?