408 stroker 8-71 blower e85...teach me

To the OP, nowhere have you mentioned a power goal for this combo yet and imo it is valuable info. At 10:1 on e85 with a roots at 10 lbs you’ll be fine but the desire to add boost comes very soon. Roots blowers have a very sharp point of diminishing returns when cranked up. You’ll get to the point when they just turn in to big heat pumps and you’ll run into problems. They are also difficult to add some kind of charge cooling to. So if you can keep the boost down to reasonable street levels, and can keep a conservative tune up in it, then I see no reason why the detonation resistance of e85 can’t keep you safe. For what it’s worth the v6 Honda in my falcon is 10-1/2:1 comp on e85 and it’s seen 26 pounds of boost without a peep from the knock sensors.