Complications of older 400ex motor in 2005?

[Fendbass22]

I am thinking about building a crazy 440 motor for my 05 for summer riding. I do a lot of 2wd mudding and riding in the winter months so I'd like to keep my stock motor w/reverse in good shape (stock).

Any issues between the two years that might be an issue? Mount offsets, oil line sizes etc. Thanks.