You can also use chocolate syrup as well - producing the same effect and at least with a syrup it doesn't have to "mix" by dissolving since it's already a liquid as well.  Same idea just a bit quicker.  THE ONLY problem with this blood or any blood using Karo Syrup (corn syrup - same thing) and chocolate - ESPECIALLY if you're doing a show outdoors.....is that the bugs love you because it's so sweet!! HAHA!!! AND it's a mess to clean up for sure.  Sounds like a good recipe.  ALSO if you don't have to have it in your mouth at any time, you can use a bit of IVORY liquid soap which helps make the laundering of the costumes or anything it touches a bit easier too and also leaves no staining because of the food colorings.  ALSO if you need it to flow well - and again don't need it in the mouth (but you can create two formulations) is to use Photo-Flow - which is a photographic "wettener" and makes the blood flow quite nicely too.  But hey, if you've hit on a good formula and it works - well then you have success!!!