Chrysler 360 w/ W2 Econo Heads, Headers, 30.over
What you are asking is how to run a race engine on the street. Your present combo is on the edge of true streetablity. Big cams and large port heads don't add up to crisp throttle response at low rpm, BUT I will try to give you a band-aid approach to get you close to what you want.
1. Swap the cam out to a XR268R. You will be able to use the same solid roller lifters, valve springs, etc. and with a roller, you don't have to worry about special oil additives and cam break in.
2. Swap out the intake manifold to a dual plane from Indy or MP. IIRC, they both offer a dual plane for W-2 heads. You didn't mention what you had, but I'm guessing it's a big single plane.
3. Go with the street avenger as mentioned. No double pumper will ever give the mileage of a vacuum secondary carb without some very intense tuning. The Avenger will need to be tuned too, but the results you want will be easier to achieve with this carb.
4. Careful advance curve tuning will help the bottom end/off-idle performance too.
Hopefully, there is someone in you area who can help you with the carb/curve tuning if you don't feel capable yourself. I love this kind of work but I'm way too far away for you. I really think that the above changes will be the only way to get the performance characteristics that you are trying to achieve.
Good luck and have fun!