Well i have just replaced my stock 305 with a edelbrock 3701 intake/HEI distributor/ and put a edelbrock 1406 carburator on it. So i just removed basically all computer controls, but when i run the car at high rpm's we get white smoke out of the catalytic converter when we stopped it looked like it had wet spots on it. What could be wrong here?

I know the carburator is not tuned properly and the catalytic converter is stock from when the car was made. Would the carburator be causing the smoke or is the catalytic converter backed up. The catalytic converter is defiantly getting to hot.

The car is headers to Y-pipe with stock single exhaust. Any help will be appreciated.

 

If you cat is getting that hot, you need to fix it before you drive it. That can light your car on fire, and has several other cars before.
Two big things stick out in my mind.
One your carb is not setup/tuned properly yet. Start with that. A lean air fuel ratio will make a car run hot. It can be bad enought to make the headers glow. If your that hot you have problems. So get your carb adjusted.
My other thought is the cat may be old and getting clogged/falling apart.

Either way you need to fix it, so you don't light your car on fire.