This is my first four stroke rebuild and could benefit from any advice out there. Crank went out and seized the motor in my '99 wr400. From what i've read the 426 rebuild is the way to go. I have an oem 426 crank and 426 cylinder along with splinned gear for the clutch side of the crank. Looking to see what parts I will need to rebuild my engine to a wr426. Will my wr400 head (still good) work on a 426 cylinder. Also will I have to jet up for the extra displacement of the 426? Getting parts together for my machinist so any advice from someone that has done this will help.