Look up Home built by Jeff on youtube, he has a whole series on trying to put an Audi V8 into a Boxster. Very thorough, but not documented like plans to follow. Kind of put together and modified as needed.
https://www.youtube.com/watch?v=qyDBHhwCHJY&list=PLnidW9Wb_Djzz1q9DZcbO9Kena81b1GuY
Also here's a long thread on an Audi V6 turbo swap, lots of modification and then it caught fire, but looked great to me along the way.
https://audisrs.com/porsche-boxster-s-986-audi-2-7-bi-turbo-engine-swa-t61757.html