Hi,
Looks for your requirements that you need a custom python payload for bypassing antivirus, so as you mention meterpreter I assume you are already familiar with metasploit. I don't mind to do your project but as you know there is no a true silver bullet technique for bypassing antivirus and once you develop one payload, you need to keep it as far away as possible from public eyes to avoid that AV companies will develop a signature, so my advice is that maybe the best approach here is a DIY.
Como ambos hablamos español, le recomiendo mirar primero Veil-Framework, usando Veil-Evasion debe ser mucho más fácil hacer lo que usted necesita. En cualquier caso, para mi será un placer trabajar en su proyecto.
Saludos!