I've used the runners off the old plenum and modified the original base plate. Deleting the twin 13B throttle bodies mounted on the side and just running a single mounted on the front.
So far the plenum is cardboard until I sort the clutch out and get the engine in so I can check for clearance with the hood.
I got a ceramic clutch with a heavy duty plessure plate and am running the W50 g/box till it blows up or I get the cash to go Supra.