You could run it. I complained about cooling last month and was basically told to shut up. Personally, I have been looking for ways to increase the cooling of my bike too. I was thinking one of those silly inline coolers.
Josh go talk to Donnie about it. Me and him discussed putting a first gen radiator on mine after I trash it (its inevitable). We compared radiators and mounting it would not be a problem with some simple fabrication skills. Just a matter of making brackets to make the holes line up, thats it for fitment. The hoses looked to be the same ID and the fan switch can probably soldered in.
The only problem Donnie could think of is the temperature switch thingy (theres a word for it) thats most likely different between the generations. It could be as simple as splicing the wires together, or making the 2nd gen one work with the 1st one, but that I do not know as of yet. Technically you wouldn't need it, ya just wouldn't know if your bike ever overheated basically.
Do the hoses go to the same locations? (lower on left, upper on right)
Fan switch temp
Will the gen1 fan clear all the gen2 frame, bodywork, etc...? (you can always move the fan).
The gen1 only has a temp dummy light, gen2 has a guage... they will not be compatible. I don't know if the hole size and thread pitch are the same. If they're not then you may be able to find a sending unit for another bike or for an industrial application that will work.