Welcome to the forum Osbertqororia, you'll find the members on here are a friendly and helpful bunch 🙂
kenya is a lovely country and I can't think of a better car to have there! I'd love to see pics of your a6 allroad in Kenya 🙂
the answer to your question is yes they can be made to fit but you'll probably have to modify the shell slightly to make them fit.
from donor car you'll need all the ecus, fuseboxes etc. Youll have to custom make engine mounts and gearbox mounts. Truthfully though I think you'd be better off keeping the 2.5tdi as it's less complicated than the later engines.
cheers
Steve