Larry, here are pictures from Chris on one of his cars...You seem to be in pretty great shape wrt completeness, and even originality.
https://pantera.infopop.cc/top...es-mangusta-interior
Generally;
- leather is natural top grain, do not use embossed ("pebbled"), smooth or split hide...There is also no vinyl used anywhere on the Goose.
- leather is glued directly (without padding) on the dash, the interior of the glove box, the coin tray, the headliner frame, the front left/right kick plates, and then continuously from the bottom front sides of the doors thru the B pillars to above all the glass and down to the floor at the C-columns...wrapping under the rear hatch releases. Passenger side may need to remove the gas tank to remove that side latch. As I can tell, black leather was used on -all- the window emergency cover plugs (no matter the interior color).
- underlay and sound deadening, 8ma1074 provided some great pictures;
a. floor, under the center console, and on top of the wheelwells is 10mm felt. This was bitumen infused on the floorboards, but see the picture of the driver side and (like the underlay around the fuse box cover) using something with a latex cover may be the best replacement.
b. thin foam was used under the headliner leather and under the leather on the door horizontal trim (at the beltline). Yet thinner padding under the leather on the rear bulkhead panels. Behind the rear bulkhead, consider something like a dynamat rubber. But avoid any temptation to go too thick anywhere...when in doubt, thin is in...
b. carpet was direct to metal along the lower door thresholds. As I can tell, there was -possibly- a thin underlay under the carpet at the wheelwells...see the picture at the firewall (with thin, probably less than 6mm thick underlay...to the side of the custom-but-tidy work done by the 'crazy Eddie' owner for 8ma1074...
The defroster vent covers are one of the Goose mysteries, common sense tells us that they should have been leveraged from a common car, but nobody has found a match to Fiat/Alfa/Lancia or even Maserati (and maybe like the rear view interior mirror, maybe just linked to something crazy like an Iso Fidia ...).