I would hold up on riveting in too many panels. Ok to fit and drill. If you do not have clecos and pliers get them for holding panels in place temporarily. It is easier to put peel and stick sound deadener on with the panels in hand.

On brake switch, put a couple of washers under the switch bracket. It should move it out enough to be adjustable.

Either remove or wrap the steering wheel. There is a lot of work left to do and damaging the steering wheel will ruin your day.

Are the rear brakes on the correct side? Mine are Wilwoods, so different. You need to put a couple of lug nuts on the rear rotors, to properly center the calipers.

Get some torque stripe or a bright colored marker. Mark the fasteners you have torqued. Builds can take 6 months or 6 years, you tend to forget stuff like that.
Not trying to rain on your parade, just some stuff I found helpful.
Keep posting.