Polished/smoothed stuff to me looks like you were wasting attention you could have spent on the rest of the motor; however, fresh or newly cad plated bolts bring things up a treat, stripped clearcoat and clean and untarnished raw alloy bits look fresh and factory, fresh hoses and rubbers really make a difference, and freshly painted rocker covers, valley covers, cam covers do bring up the look of an engine bay.
My philosophy is clean, neat and factory style rather than mega obvious wank.
Get the head dipped when its apart, will come out fresh looking. New freeze plugs everywhere. Paint the block with a good coat of black or maybe silver..
End result will be class, not arse.
Thats my two cents, and the way I'm going with the 31. Put it this way...On a TRD motor you'd see clean, raw alloy, not polished stuff, you might see anodised details and machined bits, but not purple painted EVERYTHING etc.
Oh, polish looks like arse very very quickly too in an engine bay environment, lots and lots of nasty chemicals which speed the oxidisation process, as well as staining/yellowing clearcoat if you try and protect it that way.