Actually, a lot of people do that. If you look on LS1tech, there are MANY 5.3 + turbo swaps that started as LS1 cars running some amazing times. The point is, it happens all the time. While you are at it, check out Performance Trucks… MANY people getting HUGE numbers from stock 5.3’s and 6.0’s.
Also check theturboforums.com and you will see that many other platforms are using this setup as well.
It IS that easy, people just don’t do it because they are convinced it wont work (by people that spent $10k on their motor).