Primary tube size?

I have two sets of headers, one set is full length with large dia. primary tubes and the other set are shortys and the primary tubes are smaller in diameter. My truck is a 70 chev s/b s/s and it has a 3.08 rear. The motor is a 305 w/edlebrock RPM and a 625 carb, MSD ign. and I recurved the dist and I have an automatic trans.I want low end and throttle response.Which would be the better header?  

I would say the headers with the smaller primary tubes.  

The actual sizes of the pipes would help you or us determine what to use.  

Although I agree that a smaller tube diameter affects low end torque, If I were you, I would call around to some of the better known header companies and ask the tech dept what size tube you should run based on your specific set up. If you are going to lay out good bucks for the headers then spend the time to put htem in, why not make sure you get the optimal header set up.

My buddy called Husler headers (they are the race header part of Hedman), and they wanted to know how many horses he was putting out and some other things that i dont remember. The manufacturer's advise would probably be better than anything you could find on a bulletin board. I don't have huslers number, but their website is hedman.com  

Since the bore to stroke ratio is what it is and the 305's known charactaristics are what they are, I think it's a no brainer. I bet the folks at HUSTLER will agree.  Also low end throttle response would dictate that you use the smaller tube size.