^^^^^^^^^^^
he's right you know, a stock singlecam motor only barely fits in the frame never mind some new fangled double cam nonsense.
assuming the engine mounting points and the chain run all lined up (which i very much doubt) you could possibly cut the frame top rails out, just leaving the main tube in the middle, then you'd need to find somewhere else to put the coils and stuff that normally attach to those rails
then theres the problem of where to put the airbox? what are you going to do with the oil tank you no longer need? you'd also need to rewire the bike to work with the elec ignition and far better charging system of the modern motor
having said all of that, far more inappropriate engine/frame matings have taken place over the years, follow your dreams.......
