I just put a edelbrock 1407 on my 413 last week. It replaced a 830 holley with annular downlegs. I basically had the same problems with the holley as this post and the 750 edelbrock fixed it.

The 830 no matter what I did, I could get out the sputter on quick acceleration. It was also too rich even with jet changes, power valve, etc... I used to think I knew holleys

I know how frustrating it can be, but the best thing I did was try another carb. Had a 1406 sitting here and it was like an instant fix, but the motor wanted more fuel unlike too much with the 830.

Far as et, fuel economy, etc... at this point I don't care about any of that. I'm just happy the car runs good, not pig rich and not sputtering