I think the adapter plate blocks off the coolant passage. As for the vacuum...I guess all you'll need is the vac. advance line (which I think gets manifold vacuum) to the distributor and the PCV valve. Calif. vehicles had a second diaphragm on the dist. as well but that doesn't need to be hooked up (i think it gave an extra 5 deg. advance). Everything else can probably get capped/disconnected. Just a guess, someone else who's installed the Weber will probably chime in.

-Todd
1987 Montero 2.6l 5-speed (Sold...but I still miss her)
2008 Jeep Patriot Sport 4x4