Hey Rich, I finally got the rod length specs. Stock 525 72mm stroke, 129mm center to center rod length. 576 78mm stroke, 126mm rod length (same deck height). I'm actually building a 600cc engine with 99mm bore, carb bored to 43mm, 1mm oversize valves, not sure on exhaust (suggestions?).
Here's all the measurements I took of the 3 cams. My measurements are all LOBE lift, not valve lift. I think the rocker ratio is 1:1.15.
5521 Intake 8.56mm total lift 320 dur@.006 220 dur@.050 138 dur@.200
5521 Exhaust 8.41mm total lift 308 dur@.006 208 dur@.050 130 dur@.200
8/06 Intake 9.12mm total lift 338 dur@.006 234 dur@.050 150 dur@.200
8/06 Exhaust 8.89mm total lift 320 dur@.006 228 dur@.050 146 dur@.200
HotCams Intake 9.42mm total lift 324 dur@.006 244 dur@.050 156 dur@.200
HotCams Exhaust 8.84mm total lift 314 dur@.006 234 dur@.050 146 dur@.200
Compared to the 8/06 cam, the HotCam has a much more aggressive lift and duration on the intake side along with longer duration on the exhaust (although almost identical exhaust lift). Also, ramp/valve speed is even better (slower) than on the 8/06 cam. Exhaust duration at .200in is the same, it just begins opening sooner and closes later (just like my favorite bar!). On the intake side, the duration at .200 is 6 degrees longer along with .050 duration that is 10 degrees longer.
Tony, Corse's logic seems sound to me. I hope Rich can confirm.