The plants sound good. I'm looking forward to my next angel project. I'll be getting some 50% wild/pure-strain silver crosses to try out. There are a couple of good places on the net that have worked out the genetics and offer true strains.
It seems like a bad idea now, but at the time the only tanks I had for growing out the fry were a 10 gal & 40 gal tank. The 40 gal was a community tank with my breeder angels and a few tetras. I'd grow them up in the 10 until they were big enough to hang out with the big boys.
Even with these close quarters I was able to sell hundreds of healthy fry with a nickel-size body. You really have to watch water changes when it gets crowded though. I suspect in a 55 you'll be quite happy. Little angels eat a lot and it only takes a few weeks to get them to a saleable size.
Please, please don't sell the ones that end up with deformities and ugly fins. Its kind of contrary to how we feel, but the generally poor quality of 'mutt' angels available in LFS's is a result of angels willingness to spawn and our unwillingness to be disciplined about it.
Most small angels with deformities will end up as big, ugly angels with the same problems. Just MHO, but I always took pride in a nice, healthy group of whatever strain I was selling.