2009 Runner sp 50 to 172

Hi all iv just got a 2009 gilera runner sp 50 and my plans are to put and older 125/172 runner engine in I was wondering how straight foreword it would be what if anything I would need to change ect and also if anyone else had done this before or if was even possible

 

Yes a million times before, blah, blah, blah. Do you want to bodge the engine in or do it right?

 

I'm going to do it rite as I'm going to be using it most Days of the week so no bodges

 

To do the job right have a look at a 125 runner or typhoon to see how the engine fit's, it's not rocket science to do it Wright!

 

I've not got a problem fitting it or taking the few mm of it it's more wiring side of thing what would need to be changed as I have the new shape sp50