Well, you'd probably have to start with a new stator to power the light, then the only other major difference between the R & X is the electric starter and the transmission ratios.
If you want the ratio's offered by the X gearbox, you'd have to buy whatever gears you'd need to match the X.
I don't believe you'll be able to fix an electric starter on the R. I could be wrong.
Other than that, the X & R have a different feel to the suspension, so you may have to change springs, valving & oil. Or you might be able to get away with just changing the settings.
The 450R I have was owned by a guy that ran hare scrambles, he didn't do anything other than adding the bark busters & a 9 oz flywheel weight.