ok it runs but poorly??
I guess I haven't been following your saga too close, but I'll throw out my standard load of marginally useful BS. Here are a few places to start looking.
New 1406 eh? These tend to be somewhat lean if anything, but generally pretty close right out of the box. Verify your float levels, they're not always right on new carb, everything else is cast in brass (or aluminum).
At 1/4 turn out at idle I'd guess stupid rich, but remember that the screws are for idle circuit only and mean absolutely nothing once your foot touches the gas pedal. Float level will affect you across the board. As will main jet size, so if your carb has been "tuned" return it to baseline.
What happens when you romp it good? Does it hit hard and then nose over? Does it bog and blubber as soon as you mash the pedal, but then clear it's throat and run like a raped ape after a second or two? Is it just doggy all over? Will a 5 degree increrase/decrease in baseline timing change anything? Black smoke out the back? Can you drive it normally on the street or is it really bad?
As far as that intake goes, if I had one of those lying around gathering dust, I probably wouldn't spend money on something else. It's not your main problem here anyhow. The Street Dominator, especially in the 318 port size is probably the ultimate small port intake, although an LD4B might give you a bit more bite down low. Ditch the open spacer and see what happens once you get the mixture close. If traction is an issue, a single plane may be the quick way home anyhow.