carb. crazzzzyness!!!!!!!!!

Re: the "bog" you're experiencing...you might look at your accel pump system; make sure you're getting a good, long pump shot. Could also be ignition advance not working/not setup properly.

Re: stalling cold....this could just be a choke adjustment. Do you have an electric choke on the carb?

We really need more info on your setup as it is now...cam specs, convertor, gears, etc, etc, etc.

If you decide to change carbs, I'd definitely go with a 750, either Carter/Edelbrock or Holley.