Well, dimensionally speaking, I’ve proven it’s possible. But practical? Desirable? Those remain unanswered questions.
There certainly isn’t much room to spare. Squeezing the fully assembled engine between the frame tubes was a challenging 3-D puzzle that took me several hours to solve. I was on the verge of giving up several times. Pro Tip: you must remove the upper rocker cover and the oil filter. It would have been a relative breeze without the rear cylinder studs in place, but they wouldn’t budge, despite multiple applications of PB Blaster and umpteen ugga-duggas with a pneumatic impact wrench.
My impetus was simply to make some room in my shop by getting the the Ducati motor off its furniture dolly and out from underfoot. However, I was also curious how the result would look. I assumed that getting to see it in place would boost my motivation to get busy on this project. In reality, not so much. The mounting points are do-able. The chain run is reasonable. But all I could think that whole time was that lopping a cylinder head off a Monster 620 creates the fattest pig of a 309cc engine imaginable. The result I’d end up with doesn’t seem worth the effort.