They look great man.
It's always nice to see a poly get rescued. Lap is in good hands now. Keep us updated on all your polys.
I wont worry about the sen, senegal are the most peaceful polys, i have my 3" cb koliba with a 7" sen & palmas polli, the only thing you need to worry about is the endli and ornate, endli can become cannibal when young, and ornate is the most aggressive upper jaw, it can become a killer.
I wouldn't worry too much about their size difference. I would add the other 3 bichirs with the Senegal during a waterchange.