FIC offers a very easy to use calculator on their website. Even at 300 hp (crank hp) you would need a minimum 350cc on Pump and 455cc on E85....thats at 90% duty cycle and 43.5 PSI AT BASE PRESSURE. As noted above you need at least a 30% increase in flow going from pump to E85 as ethanol consumes 30% more fuel.
Moral to the story....you need much bigger injectors to get even remotely close to any goal in the 250+rwhp range. You would be maxing out at somewhere in the range of 200rwhp with those injectors.....not worth it. And if you do decide to upgrade injectors remember you need to make sure the rest of your fuel system is compatible with E85, you have an ECU/Standalone that can handle the changes, and go for at least 1,000cc's.
Flow Calculator
http://fuelinjectorclinic.com/hp-calculator