450r engine in a 400ex

[FutureRacer]

How hard is it to drop a 450r engine into a 400ex frame and also about how much does one run from a private seller?
I am really interested in doing this but i need to know some pointers from people who have done it. How bad do i need to modify the frame and will i need a new subframe to mount the exhaust? Is there any kits made that make this easier and possible without sending the frame off?? Thanks, Kelley

no harder than dropping any other motor in it.

$1500-$3000

you need radiator to.

no kits but easy to do. I had a guy put my yz motor in and it took him 7 hours total.

If you cant weld some one has to do it for you. No matter what their is welding and a little cutting. not much.

costed me like $270 only to get my frame moded to hold the motor