I researched this for a paper last semester (persuasive paper on the advantages of E85) and found that the conversion is not too difficult, though I didn't address the conversion in my paper. There is a lot of information available on the topic and several universities have done E85 conversions successfully. Basically the mixture needs to be enriched (for max power - lean limits are similar to gasoline) and you can run more advance. Engine temps are lowered and cold starting becomes more difficult. One of the conversion projects used a MSD 6 box to overcome the cold start issue. E85 is agressive towards certain plastics and non-anodized aluminum (Edelbrock said my 1406 is compatible with the fuel). I also found out that the old "high test" gas contained a large amount of ethanol to raise the octane, so I would suspect that most of the old muscle cars would only need a jetting change. A quick search will turn up lots of info (including materials compatibility).
Attached is a (poorly formatted) text file of my paper if anyone is interested.