Eon, it’s certainly a large engine, but I believe what you’re noting isn’t the size, it’s the way the engine sits in the frame. Moto Guzzi uses a transverse V Twin. While most manufacturers mount their engines longitudinally, MG does things a little differently. Imagine taking any V Twin and rotating it 90º, the cylinder heads would protrude like they do on Guzzis, it’s certainly one of the most recognizable trademarks of the brand. Not really sure of any advantages or disadvantages, I do know that it gives them an unusual side to side sway when stopped at idle.
On a personal note, Moto International in Seattle is widely regarded as one of the more knowledgeable Moto Guzzi dealers anywhere. The owner is the author of the book Guzziology. Maybe not on Amazon’s Top 100(or top 1,000,000) but revered in certain circles.