Yeah, every one is going to be a little different, you might think it's the same engine, but it doesnt take much to make a difference. Like I said, it doesnt matter too much, except for bragging rights. Get it done on a chassis dyno if it's really important to you. Most guys that I know who have done that have been Greatly dissapointed!! As far as the Desktop Dyno, I dont go by it as gospel truth in the numbers, but it's fairly accurate when you put in correct info....I use it mostly to see what swapping cams, carbs, intakes, heads, etc. will do to the numbers.

Oh, I mis-typed, your torque was 471 at 3500, not 371....and with your steel head gasket, it's .020 thick, which makes your C/R about 9.5, a half point higher...new numbers are (drum roll) 391 HP and 481 torque