Thanks for the answer on the wire harness routing. I think we'll do the same on the passenger side with the MSD harness--securing it with straps/holes in the outer fender so it's out of sight.
I'm pleased the '66 GTO Ram Air carb pan and the Firebird hood pan end up at the right height to make this setup ideal for the Firebird. The only mod needed is to narrow the hole (circle) in the hood pan as it is wider than the '66 GTO carb pan--only by about 1 1/4" on each side.
It's really tricky, however, to get the mechanical Tripower linkage tucked in with the TH400 kickdown switch. Looks like it will work, though. I may have to use the '66 Olds slotted rod operating the front carb instead of fighting with lack of clearance between the kickdown switch and the throttle cable tower.