The fiberboard duct goes in after the apron is on before you put the grill on. I also put the support cross piece on the apron before putting the apron in place. It's easy enough to get those four screws in that attach to each inner wing. Leave the wing screws loose along the inner wing so you can jockey things in alignment. I used a tapered punch to align the holes. I put the hood spring mechanism in after the apron was on, and it was a bit tedious. You might want to put that on beforehand also.
I also opted to pop rivet the tabs holding the bead to the wings. If you leave some of the front wing screws out, you can spread the wings out enough to plop the apron in place. Then just push everything together. It becomes a one man job then with no muss or fuss. Just leave all of the screws loose until you have them all started.
The headlights can be put in afterwards, and the Medallion and letters can go in before or after the apron is on, but before you put in the grill.
Also, leave loose the brackets that attach to the frame that go through the front of the apron for the bumper mounting. Again, to make aligning easier.
Everything up to the front of the radiator should already be in place, so just check and recheck and then just go for it. And, I'll say again, keep all the screws loose until you have them all started and everything aligned nicely.