After several tries they are available:

Bumper fillers for Iso Grifo (and Alfa Romeo 2600) front and rear bumpers.

These are hand cast reproductions for the obsolete but necessary bumper filler seals for Iso Grifo and Alfa Romeo 2600 cars. Cast from NOS originals, these are authentic looking into the smallest details and will fit original bumpers perfectly. I made sure these fillers came out AS perfect as factory original and even had the (invisible) mounting holes filled so they would fit any arrangement of mounting bolts between the bumper ends. I had my name (invisibly) engraved to guarantee the quality of these.

Manufactured in USA; high quality workmanship and preformed fit. Highly UV stabilized, actually better than factory. Correct hardness and sheen, perfect into the smallest detail. I have a limited number available and sell them as single seals or sets of one left and one right hand seal. Front and back are the same. Links:

https://www.grandtouringusa.com/shop/iso/iso-parts/filler,-iso-grifo-bumper-l-or-r-detail

https://www.grandtouringusa.com/shop/iso/iso-parts/fillers,-iso-grifo-bumper-pair-l-r-detail