Rook, I wouldn't touch it. Gen 1 is 1352cc and gen 2 is 1441. Figure it's going to be a mm change with matching more of a 1441 to a 41, and some 1352's wont fit a 41.
Only the parts pages matching numbers knows for sure. Look for a compete engine of your cc engine size.
Kind of see the proportions of just 2mm of the rod growth to sort of square the engine some? Kind of take a mm is the up stroke, the other mm is the bottom stroke. That will grow the engine case a mm difference is you have to compute that factor creating a new engine case of changed clearances.
Where the crank may have a straight cut to clutch outer basket, and yours might have a conical cut.
https://st.hotrod.com/uploads/sites/21/2010/10/1010sr_25_o-quick_change_rear_end-straight_cut_and_helical_cut_gears.jpg
So basically nothing fits and it snowballs from there part to parts wise. Complete engine is the less $headache$ move.
Tormenting the motorcycling community one post at a time