Hey buddy, that doesn't sound to far off from what i calculated, but you can't believe these hp calcs, they are ok for a before and after though, but not a true baseline:

I calc'd: 319 at the wheels, based on your 1/4 mile time and speed.
Then awesome you're loosing, 28% thru your trans and axles, that's 407hp at the crank.

Sounds right to me,

allen