I think "AL427SBF" actually got it right...."don't need the extra power".
That was my smart ass remark to your
Also please don't tell me I don't need the extra power... 
It seems more often than not, when you take an already BUILT race motor and try to squeeze another ~35% out of it, inevitably you will run into that can-o-worms RICK LAKE pointed out, and with the blykins catastrophic failure always pending. Drive it like there's an egg under the gas peddle and you might get away with it,
Of course
The guys @ the dealership who ordered the motor for the original owner said it could hold over 700HP with no trouble, but remember they are are out of $$ and holding a loss until they sell it.
You've already got a kick ass motor, and with some margin to driver it hard - enjoy