Peerless, Triad and Chicago stopped making Pultec transformers years ago, and beyond that some of the lamination material is no longer made. The same goes for many of the old capacitor companies (Astron, Aerovox, etc.) as well as the processes and materials used to make these old products.
Same with the inductor.
Furthermore, the costs to have all of these parts reverse-engineered and the raw materials reproduced, the manufacturing processes reproduced, and the actual components reproduced is prohibitive. Besides that, nobody's going to do it anyway - the production numbers are just too small for any manufacturer to tool-up for.
Ultimately, even if modern replacements could be fashioned, these parts would only be copies of the originals and not identical.
Otherwise, to create a Pultec duplicate without new production parts would require that a supply of NOS components be sourced, which is impossible. Even if they could be found, some parts (capacitors) would be way out of tolerance after 50 years and as such, unusable.
Which means that building an "exact" duplicate of a Pultec is impossible.
But, that doesn't mean we can't build the same circuit using high quality new components (as well as NOS parts) and achieve the same performance.
Will it sound the same?
It will sound very similar to what Pultecs sounded like when new, as the EQ curves will be accurate and the rest of the circuit (and tubes) will be in close tolerance to the original schematic.
But, will it sound just like a vintage Pultec?
Vintage Pultecs are subject to variances in tube balance and performance, capacitor and resistor drift and generally wide OEM tolerances. This means that no two Pultecs will sound exactly like one another. It follows that a new reproduction will not mimic, exactly, the "color" of any original.
Okay, but will it have the Pultec mojo?
I believe that much of the magic is in the original circuit design, rather than any specific components, and as such, yes.