Intake swap

Could anybody tell me, can I swap a Blue Thunder Intake on to my 351C engine that currently has an Air Gap and still use my Pro Systems carburetor? I have 4V CC heads and would like the ports to match from intake to head. I understand I won't have the same port velocity so my bottom end might be a little more sluggish. Or will the carb need to be re-tuned?

I don't see any reason you can't. As to retuning of the carb. odds are it will perform okay as is, but a slight rejetting would be something I would plan on and if the engine vacuum changes, then power valves may need to be changed out as well.

Does anybody think I will lose power going from an Air Gap to a Blue Thunder? I know with the Air Gap there is a BIG port mismatch, And I have often wondered what, if any kind of effect this has on power. I like the blue thunder because it actually has 4V port sizes and there is no port mismatch, although this slows down port velocity I have to believe that it is more efficient. If I do have to do a jet change should I go up (more air=more fuel) or would I go down (slower velocity=more time for fuel delivery), or is my thinking backwards?

The velocity that will go down is only in the intake runners. The velocity in the ports, and more importantly, the carburetor will go up, as the smaller runners restrict the air flow, especially at higher revolutions. You may wind up with a lean condition.

The Blue Thunder manifold is one of the best for 351Cs. I believe your overall performance will improve. My 351C with a Shelby (same as Blue Thunder) intake feels great throughout the power band, including initial acceleration. It will be interesting to see if you think the off idle throttle response has suffered, I haven't been able to make that comparison.

I would install and run as is and determine jet changes based upon how it reacts. It is still the same engine, has the same pumping capabilities-I would expect any change to be minimal and would not predist which way it might go.

My Pro Systems carb works and fits very well on my Blue Thunder intake.  I'm not sure the difference you will feel when swapping but I can't imagine it will be much if anything negative to say about it.  All combinations are different but I'm sure you will not absolutely regret it.