I agree with George. Leave it alone and run it as is.
If you are looking for more power out of it, and I don't know if there really is anything much to be gained, other than entirely ruining the manifold, get the Blue Thunder Pantera version and send that out for modification.
As a matter of fact I am quite sure the BT is already available from them with the plenum divided modified. It's just a matter of the size of the "balance port" (notch).
I think if you want to try something different, look for the Dominator version and use the newer Holley 750cfm Dominator on it.
In all these years, still haven't seen one Pantera running that set up.
If for no other reason, that monster carb would definitely draw some attention and is plenty big enough for a single carb induction.
For some strange reason, Pantera people aren't impressed by Shelby logos on their cars. They seem to be more in sympathy with the Commodere's perspective of American-Italian relationships? Best not go there at all.
I do have personal first hand knowledge of that manifold. I ran it on a Boss 351 with a Shelby solid lifter cam and a Holley 4779 750 dp carb.
It is impressive to look at but I personally found that the Edelbrock Torker way out performed it.
Now that's an interesting observation since all current dyno testing has shown the opposite in results and that the Torker is one of the worst manifolds built for the Cleveland.
I tell you this since you might want to qualify my info and I seem to be a contradiction to whatever seems to be documented scientifically?
I too am also an old fart, with lots of grey hair...but I got hair, lots of it! So take any advice here with a grain of salt, and don't forget to throw it over your left shoulder too?
Also remember that there is usually one in every group that seems to be the burr under the horse's saddle or maybe the hand up the Mona Lisa's skirt? Hey...why is everyone looking at me...and why do think she was smiling anyway?