That car has not been heavily modified, I wouldn't bother trying to change the carburetor, although I might change the manifold to a standard Performer. I have a 73 Camaro with the regular Performer and a stock QuadraJet, and I will try to take the time to figure out the hood clearance with that.
Their are two incidences of fuel hose on the chassis, other than the engine compartment. One in the vicinity of the door, where the hard line of the unibody connects with the hard line on the subframe, and another where the unibody line connects to the tank. The first is easy to fix for someone under the car, the second can be a real pain.
My .02 is to put the throttle return spring on the A list. I haven't looked lately but the bracket to do that properly is almost certainly available online.
What is the muffler situation? Does it still have the crossflow muffler, or has it been converted to duel mufflers? This will factor in to how you deal with the tailpipe issue.
At any rate - nice car!