OK guys I think I have the FINAL answer with all this, Summit UP312Q Black Satin. It gives the best color match and even has the right amount of texture to mimic Organisol about the best you're gonna do without spending gobs of time and money.

In case you care I also I tested an idea with a painted sheet topped with 1) Summit UP355Q Hot Rod Matte Black (left panel) Summit UP312Q Black Satin (right panel) and equal mixes of both for the center.I rolled it on (hence awful texture) let it cure and taped off the top 1/4 for "before/after" and wet sanded to 2000 and buffed to see if I could manipulate sheen, As you can see they all turned the same level of gloss. So I selected the Black satin with no buffing, and it turned out GREAT!

One note - Dave my paint guy said after he laid on the Satin and it began to cure it had gray blotchy patches, he was concerned but HAD to get the stencil off before it adhered so just hoped for the best...next day, all good!