I know with the DSM ECU when you start increasing injector size (you show the computer less airflow with the AFC to compensate) the computer starts adding ignition timing, so I would only step up to a 42# (~450cc iirc) injector since its ~20% bigger than stock bonnie injectors (iirc again) and E85 would take ~20% more fuel. Then, the AFC would only have to cheat the computer for a smaller amount of airflow to get to stoich and the timing wouldn't be as far off, and if there was a small amount of timing added the E85 would have no problem keeping KR (knock in my lingo) to a minimum and if you ended up losing timing that just means compensate with more boost
I dont know what the stock fuel pump is capable of but an inline would be easy enough to add if necessary.
42.5# Lucas Injectors - $239.99
AEM UEGO Gauge-Type Wideband - $218.11
Walbro Universal External In-line Pump - $119.00
Apexi AFC Neo - $359.00
$936.1 Total, which is fairly steep, but all that stuff can be had for cheap on my DSM forums since a 450 injector (low impedance though so a resistor pack would be needed for this application) is stock for us DSM Guys!
and most people start with AFC'* then step up to stand-alones for high power motors (675+HP, 35+Lbs of boost) I have seen injectors given away and AFC'* as low as $100.