^^ Is this a trick question? lol
-5's on built engine with E85 would be the way i would go and if it is in the budget get the 2.8 as it would make them that much better. Here are 2530's (-5's) on a 2.6 with E85. Compare this with other set ups with a 2.8 and the difference is night and day.
Couldn't find the one with RPM.