My memory is fading on 3800 stuff so forgive me and listen to others.
Trans is different, but import the 04 file and you should be all set. (04 regal file with L67 should do the trick). You'll need a tb adapter to use the newer sc with the 00 tb. Yeah.. as I think about it.. the trans should work and the engine only needs your rear exhaust manifold and a tb adapter, then you'll be right back where you were.
Otherwise you'd still have to do the trans stuff and then you could swap the LIM and SC/tb on to have the same basic engine.
Those are the ways I'd do it.
