I've run both on engines such as you describe...couldn't have been happier with either. Both are really good carbs.

Either are very tuneable...and can be made to get pretty good mileage.

First, DEFINITELY stick with a vacuum secondary...your satellite is a little on the heavy side, and the DP won't like heavy w/ a somewhat stockish torque converter...even though you've got decent rear gears.

I'd disagree that size is terribly important to an extent too...that's what's great about vacuum secondaries...too big a carb with vacuum secondaries, then the secondaries don't open all the way...only to what your engine is asking for.

That said, for a mild-ish 318, you can't beat a 600cfm. Heck, I used a 600 for a 360 that saw me into the lower 13's You'll get better mileage and throttle response with the appropriate sized carb.

In my opinion, you can probably tune an Eddy for better mileage than a holley, and you can probably tune a holley for better performance...but if you are hoping to avoid tuning, either is fine.

But since you are asking about the street avengers, you might be looking to tune at least a little, to which the holley is probably a bit easier for what you'll want to do. That said, eddy''s are pretty simple too.

Most who like one, stick with it...but myself, I'll go easily b/w each, no qualms about it. Heck, I've even been known to like a Quadrajet or two in my day lol.

To me, my guess is you'd probably be happiest with the holley street avenger 570. Check float level, set lean best idle, put in progressively lighter secondary springs until you get a hesitation/bog when flooring it, and then back up one spring size...and you're set. Easy, efficient, reliable and plenty quick.