Yamaha dragster 400 conversion to 650

[Ford]

Hello guys, I'm a new guy to bikes so please take it easy on me, long story short...Yamaha says my crank shaft is broken and to replace it with Labor and everything...it's gonna coast me the price of a secondhand 400 what I have the option to do now is to put a dragster 650 engine in which is gonna be the cheapest and most convenient solution to me. 

Now my question is will the 650 engine fit on the 400 frame? 

coz as far as I know everything else is the same. Please advise guys thanks allot

- Ford 

[Campaman]

From what I have read it should do as its exactly the same bike available in Classic and Custom varieties made for the Japanese home market but with the smaller engine capacity.