Slant six intake/carb question.

Was the car running previously, and of so how well? If you are just getting it going, and you did a good rebuild job on the carb - and also assuming it's in decent shape - the rest should be tuning issues. It should run fine with a rebuilt carb, all other things also working out. And i agree with 66fs, there's no reason to swap out the manifold.
The car would idle when I first got it. I replace the brake lines and I couldn’t get it to fire off after it sat for a few months. I rebuilt the carb and it fires off great and idles fine. I can drive it a short amount of time but when it gets warm it will die and keep dying when I give it any amount of gas. When it’s cold it runs great. I plan on doing a complete rebuild after the cars in my name. I just hate to put too much money into it until I know it’s mine haha.