Does anyone know of a company that sells these decals for a 68 Hemi hood? Thanks

Try Ebay for custom letters.

or possibly, a local sign shop ?
some shops do this, others don't. of the couple local shops here, both do not, but a girl a couple of towns over [who is an artiste] used to do that occasionally. not sure if she still does that or not.
just something to ponder.

There's a smallish sign shop - they do vinyl banners and adhesive vinyl stickers - near me.
One of the things they've made for me was a 426 Street wedge air cleaner top decal.
They even figured out the proper wedge-gap so it laid down properly.
There's probably sheet vinyl with an engine-turned look.

Some good local shops could custom made them. We have one that can do the 90's decals.

You can buy vinyl with that look off Ebay and other places. Most sign shops won't have any vinyl like that just sitting there so if they don't you can buy a small roll and bring it to them. They will cut the gold out first and then apply the black border over it. The gold material will be thicker than what they usually cut so they may have to up the plotter cutting pressure. It's easy enough to do.

The lettering on that scoop could very well be painted on also, but it's hard to tell from a picture.