i'm not sure which way your going with this but the 9000 engine should fit into a 900, its been done, however you might struggle to fit a 900 engine into a 9000, the reason i say this is cus i am in the middle (long project) of fitting a 9000 engine into a 9-5 and the 9-5 has some of the mounting points needed in the 9000 missing so it could be that htese mounts are also missing on the 900 engine