Personally I'd get a sample bait to have right there at the shooting table with me for direct comparison. Next I'd do a 4 ounce batch and be certain to count drops of Florida Grape until it got dense enough to add some black using a toothpick dipped shallow in the colorant and stir it in. You could also start with a smoke made from black and plain plastic. Then add drops of the Florida Grape to get it to where you're ok with it.
On these heavy colors don't add any hi lite or glitter or pearl until you get the color right. Don't add anything to make weight either. Lay the sample bait and what you've cooked up on the back of an aluminum mold and get this under some light or sunlight to check for closeness of color.
