You are in the states. Peathenster has Geo orange head Tapajos juveniles for sale. Get a group of six and raise them out in your tank. Even with the shipping cost they will be a great price. Because they only get to about 6", they should do well in your tank. They will also be peaceful toward the angels.
I would avoid severums because breeding pairs get very territorial. They would probably wreak havoc on your angels if that were the case.
Pomatomus, Bolivian rams don't grow that large. Either you overestimated, or the 5" fish you saw was a Biotodoma species that sometimes look like large Bolivian rams.

I have seen them mislabeled at stores before.