72 Duster Resurrection

The accelerator pump is a plastic piston which is at the bottom, connected to the throttle mechanism. The diaphrams tend to tear and leak gas out the slot, but new ones are in the rebuild kit. The 3 screws in front of your circle are the top of the "economizer" which is similar to the "power valve" in 4 bbl Holleys. It richens the mixture at higher flows (lower venturi pressure pulls the diaphragm opening 2 fuel ports). Also in the kit. The Holley 1920 can drive people nuts if the sealed metering valve is clogged, so you get a lean idle. For startup, run a hose to a jug of clean gas. You can also spray starter fluid down the throat just to test (don't run long).

Don't run more than 30 sec without coolant. You can run a garden hose when testing, which will also help flush the block. Once driving regularly, run w/ water and 1 lb citric acid (ebay) for a day to get a good flush.

Looks like you have front disk brakes (MC has a large F reservoir). That would be the valuable Kelsey-Hayes disks in 1972, also used in Mustangs. A used setup runs $200 on ebay, so consider you paid only $300 for the car. Rockauto has rebuilt calipers. Your wheels are somewhat unique "small bolt pattern" 5 x 4" bolt circle. Don't fret, since many sell their alloy wheels cheap when changing to later size, or you can buy new 17" alloys in SBP.

Many parts have options. For the electronic ignition, consider GM 8-pin HEI conversion (TrailBeast here sells kits). For AC compressor, consider a smaller Sanden. For starter, look at later Magnum-engine mini-starter. You can change to a 2 bbl or 4 bbl intake manifold, or even retrofit MPFI like pishta did. Take it slow and read up before jumping into anything major. Like most, yours is rusted below the brake MC (leaking glycol, plus exhaust heat). De-rust and paint that when you have parts off. Overall, your engine bay looks really sound. I hope the hood rust is just on the surface since rust-thrus are a whole bigger issue (need weld repair). You usually have that around the rear wheel wells and door front corners.