That is one option the smaller severum should be fine. I say should because all fish have there own temperament. In my opinion breeding brings on so many headaches. I do everything in my power to keep my fish from breeding. Be prepared to have multiple tanks ready to go. A breeding pair will claim the whole 65 gallons. All other fish will be cowering in the corner. Breeding cichlids brings out the most psychotic behavior is chichlids it is so frustrating when you have nice peaceful tank and then all of a sudden everything is out of balance.
In order to sell severum you should be able to house the for a 6-8 months so a breeding tank is necessary or they will become food when they adults are ready to breed again. When a breeding pair forms they don't stop. Pretty soon your local market will be flooded.
I'm not trying to say don't do it I just want to give you the heads up I wish people gave me. IMO it will be much more pleasurable to grow out a beautiful adult severum as a center piece and then have a nice school of tetras surrounding it.
You sir, seem to know what you're talking about. And you brought up lots of very good points that I didn't consider. While you didn't intend to scare me, it did in the best way. I'm now completely aware that breeding (severums at least) is not something I want to do and definitely not at this current time. your knowledge has helped me make an informed decision. Thank you.