Yep, putting one in my '82 Honda Sabre roller project.
The Predator 670 is about 18" tall with a footprint/base of 6" wide and 9" long. But, that doesn't account for the fan shroud, PTO shaft and cylinders sticking out from around the engine.
Also, it had a huge exhaust/muffler mounted on the drive side. You'll want to cut this off the header (middle of the header pipe) and then use a flex exhaust pipes (like from Rockauto) to relocate it.