Not the greatest intake, too small of a carb. In my experience a holley will always outperform an eddy carb all day long.
What height tire are you running? A 3:73 or a 3:91 is pretty livable on the street. 4:10's+....not so much. Unless you have an OD.
What cam is in it? What heads are on it?
I hate to tell you this but literally every 383 car I've ever been in was a dog. I know there are guys that have had screamers or had a buddy that had a buddy that...
This /\ /\ /\
Putting headers on it isn't a bad thing. Getting it on a chassis dyno will get you tuned properly. I wouldn't spend a second thinking about whatever number it spits out. I've seen 70+HP variations in chassis dyno numbers. No variation in AF ratio's and timing.
IMO I'd get the 3:91 gears, get a 750HP series holley or knockoff like quickfuel etc. Have it tuned. See where you're at. You can live with that intake. The headers are fine.
