Here's the engine compartment at the moment. I ended up using a little daub of diesel fuel on a rag to clean the firewall and the inner fenders. It worked out very nicely. The dry areas you see on the driver's side of the firewall and alongside the A/C box are the sloppily-applied, factory body schutz undercoating, which I am leaving in place.
And, yes that is a rag covering that cursed open exhaust down pipe.
Some of the cleaned up parts at the moment: the steering box, wiper motor, the steering shaft, the 7042264 1972 400 carb (matches the intake I have on the car), and an extra brand new master cylinder that I had sitting around waiting to go on something.
My parts order from Summit Racing should arrive tomorrow so I can bring the pistons, cam bearings and block assembly hardware over to the machine shop. I ended up getting the entire rebuild kit, which includes .030 pistons, rings, cam, main, and rod bearings in one package. (The crank polished up nicely so I can stick with standard size main and rod bearings.) Since I already had bought a new Melling oil pump and a Felpro gasket kit, they were able to deduct those items from the kit and save me about 80 bucks.