Spent today trying to nail down the plenum placement. Clamp plenum in place and used some molding clay cones on top to determine gap to top cowling. Clamped and readjusted plenum numerous times to get the 3/8 to 1/2 inch gap necessary. Got it as close as I could and drilled a hole for #40 clecos at each corner. Edges are pretty well locked in. Need to secure and drill holes to lock down center aft and forward section of plenum to baffles. Left inlet diffuser still wants to drop down from alignment. Will try and improve that with holes and clecos in plenum.