I've got a ZDZ 80 on a 28lb edge. Vertical is unlimited and hovering isn't a problem. I am running the cheap $50 muffler. I noticed you want to keep the cost around 500-600. You can get the ZDZ 80 brand new for $555.00 and the cheap muffler for $50. That will put you $5.00 over your limit. I had a 37% challenger 2 bipe with a brison 6.4 twin on it and it balanced a little tail heavy. Mine weighed 31lbs, so you might have a problem with balancing the big bipe. Just a thought. I had to add 1.75lbs of lead to the front of my edge with the ZDZ 80 on it.

Andy