Good luck with your equalizers. I don't know that much about them other than that they are supposed to share a lot in common with Automags, and so probably share the automag's distaste for CO2. Nitrogen and compressed air are interchangable for paintball purposes, and might be the better gas choice for this gun.
BUT, this is mostly just speculation on my part. Try asking your question here: http://www.mcarterbrown.com/forums/sheridan/
The guys on MCB really love old guns, and I've found it to be a very helpful forum.