Just try it. Put the E85 in there and get it re-tuned. 99% of cars make more power and make it earlier, so your car shouldn't be any different. The 2560 you have should be good for up 220-230rwk or so (from memory... its been a long time!). If it doesnt make more up top due to other restrictions (cams?), it will make more mid range.
If the fuel pump and injectors cant handle it, upgrade them or revert back to 98. I think the 460cc are too small but like above get a fuel reg and up the pressure. Thats what I did when my 740cc maxed out 260rwk
Not sure why you are procrastinating when you have access to a dyno that I assume is free.