The DT200 motor is the same motor as a Blaster but it's water cooled and have another thing i don't remember and it gives some extra hp. I think you can get the head off ebay.
theres someone over here in australia thats got a blaster with the dt200 water cooled head on it,its a mx bike,the bike is about 3secs behind a slighly modded lt-r450 with a decent rider on it.....
water cooled would be a good idea if you lived in hot climate...but..where i live...aircooled = good nuff... it would look kinda funny in my opinion to have water cooling head on a blaster.....but still, its a decent idea!