I would guess that to really be sure of this, you'd need to take measurements. The engines are visibly VERY similar but I don't know who you'd have to ask to get that very specific info.
You could go to your dealer and ask very nicely if you could take the measurements from the dommie in return for a little business.
Or, you could get the engine and then go to a welder if the mounts need to be shifted around, but you'll spend a lot of money to have it done right. I've seen lots of hybrid motocross bikes built like this. For example, people take aluminum CR perimeter frames and put the new Yamahs YZF 4-stroke engines in them.
Where there's a will, there's a way. But keep in mind that creating this beast could end up costing you more money and headache than just getting the right parts.
Wow, that's a pretty ambiguous answer now isn't it?