lake_harley - I believe your reference to the 30-35 percent increase regards actual E85 fuel flowing through the carburetor from idle to WOT versus 90 octane gasoline. You are right it does not refer to a larger "jet diameter." The solution is not as easy as drilling out the two jets on your existing quadrajet carb to increase the "area" for more flow.
If you wanted to do this with precision, flowing the individual jets would be one method; for a mechanical fuel injection system that operates at higher pressure/flow than a carb jet, FIE has the setup to professionally flow individual jets. It may not matter as much with a carb jet. Drilling out existing jets to increase flow has been done by many others over the years in many different type carbs.
I've not sure how a quadrajet carburetor would run on E85. As a starting point for your particular engine, I think the 30-35 percent increase means both in the primary and secondary flow. Drilling out the 2 primary jets (i.e. increasing area) may only be a starting point. As you know, there are businesses that sell new E85 4-barrel carburetors, and they sell for $700-$1000 each. The new E85 carburetors do not resemble a quadrajet style carb, there must be a reason for this decision.
You mentioned methanol versus E85 and slightly lean burning holes in pistons. I do not have much experience with the internal workings of a quadrajet carburetor and only somewhat familiar with how they operate. For your idea of using a quadrajet carburetor for E85; if you were to only modify the primary side to increase fuel flow by 30-35 percent and not modify the secondary, I could guess you may experience a lean condition at WOT that might do damage.
My experience with methanol with a mechanical fuel injection system has been it tends to run richer as you go to WOT, and therefor in some cases a need for a high speed leanout. Setting my tuneup with methanol, I have it set up very very lean to start so it can build engine heat quicker on startup. Once you rpm up, go do your burnout and make your way to WOT, the system goes richer with mechanical fuel injection. I'm guessing with E85 it would be similar with mechanical fuel injection, you will have to let us know how it works with a carburetor. Alan