Could you do it, yes but it does require you to do more than just swap parts over.
You'll have to buy a throttle body adapter plate because the TB bolt patterns are different, you'll have to drill and tap the TB for the PCV system because the L36 manifold uses a different system than the L26 manifold. I'm not sure if the L36 fuel rail clears the L26 intake and you can't use the L26 rail because it's a returnless system. There are several threads on the topic of UIM swaps with most of the answers you need.
To me it's easier to just buy new lower intake gaskets and grab a new L36 upper intake manifold for like 80-100 bucks or whatever they sell for now. That is if you think your UIM is in bad shape.
