Problem off the line

I have a 66 stang with rebuilt 289, plenty of power, and rebuilt c-4 tranny. The rear end is the original 8in and I suppose 2.80 gears, but dont know for sure. I am having a major problem coming off the line. Are the gears the main problem? What is a good but relatively inexpensive replacement/fix to the problem?  

what exactly is the problem ? wheel hop ,wheel spin ,the car not coming off the line fast ? is the engine stock ,does it have an aftermarket cam ?  

What kind of cam & carburetor? What is your ignition like and what is intial timing?
Vacuum leaks? Stock torque converter?
Should still do OK even with a 2.80 rear end. Most likely a tuning issue.
Does it just feel like it goes flat until you pick up speed or does it bog right off the line? Need more details please.  

Ok here it goes:

289 completely rebuilt. Shop guy said he bored it to equivalent of about a 304

It has:
Edelbrock performer intake, cam, and lifters.

Holley 670 cfm carb (little bit high on cfm's but got a good deal couldnt pass up)

Tri-Y headers, dual exhaust (2 1/4 tubing)

Tranny is completely rebuilt c-4.

Problem is, coming off the line, I try to give it gas and it just coasts, hardly any acceleration until it hits right before 2nd gear, kind of like you said "It goes flat". Once in second gear, i can punch it and it picks up and takes off, and when it needs more power it has no problem kicking down and drawing more RPMs for me. The only real problem is off the line. This may also be related to another problem: when i first start it for the day or after it sits for a few hours, when i go from park to any gear (reverse or drive) it needs me to feed it some gas while my foot is on the brake in order to stay alive. After warming up though, there is no problem going in and out of gears.  

You might have your tranny rebuilder check your tranny now that it is in the car and running. He can see if anything is wrong in a road test that couldn't be seen sitting on a work bench. The tranny might not actually be in 1st gear when you start out and is bogging the engine down. It could actually be starting out in 3rd gear. Try leaving the line after putting the shift selector in a lower gear than drive and see if there is improvement. The fact that it runs good once it gets to second gear makes me think something is off with the tranny or torque converter.

You might also check for any vacuum leaks as they will hurt performance more off the line than at higher engine speeds where the leak will be absorbed @ higher rpms.
Make sure your ignition is timed right too. You should be at about 10 degrees BTDC @ idle with that E Perfomer cam.
Make sure your carb choke setting is right for your car too.  

I had a very simular problem on my first car, (a SB Nova with a 650 spreadbore) too much carb! I think based on what you've told us your story is, you have too much air for that engine to swallow all at once off the line, thus a bog.