I havent liked the Avenger series in any size. In both the 670 and 770 version I have found that low rpm transition can be lean, and it generally takes work on the main well, specifically blocking the lower feeds, to get the booster to come in when it should. Some can get away with an aggressive pump cam to mask it, but it is a tuning flaw IMO
I have not used the 80508, but if it matches a 3310, I think it would be fine. Do you need electric choke? If not, its hard to beat a classic 3310, if cheap enough you could even buy and add the electric choke yourself.
Another comment, although typically most of us dont use Edelbrock carbs, in your low RPM use, they can work pretty well and are very tunable. An electric choke 750 Edelbrock is a nice driving carb