Help with my 390 FE?

I am new to the forum and am looking for some help. I just picked up a Everett Morrison 1967 Cobra replica that has a Ford 390 FE in it. It sounds like it is not running on all cylinders so I took off the plug wires one by one off the distributor cap and on cylinders 1, 4, 6 & 7 it did not make any difference if the plug wire was removed. This does not seem right, as when I remove the other plug wires the motor bogs down. I tested to see if I was getting spark at the end of each of the plug wires and swapped in new plugs but nothing is changing. Any suggestions on what is going on or what I can try next? Thank you so much

Remove the valve covers, disconnect the hot wire from the coil and turn the motor over with the starter, observing for equal movement on all rocker arms. If some of the rockers aren't moving much, the cam has probably gone flat, requiring disassembly of the motor to clean out the shrapnel, followed by a new camshaft and lifters.

If all the rockers are moving equally, remove all the spark plugs and wire the throttle blades wide open. Do a compression test on each cylinder.

do you have a 180 degree manifold???

if so then probably one side of your carb is screwed/plugged up

Thank you guys, I think you are right after looking at the flow pattern on the dual plane Eldebrock manifold that I have. What can I look at in the Eldebrock carb that I have to see what is happening? How would I repair that? Thank you so much