Best place to get DGV is from Redline or other authorized distributors, eBay sellers ask more! And with Redline, you get one with a baseline tune that works OK with most stock engines (just need to adjust idle speed & idle mixture). I don't know anything about reproductions, didn't know they made em for the DGV. Holley made licensed versions (Holley G180, Holley 5200, etc)

When you get a DGV, unbolt the throttle quadrant, and bolt the Hitachi quadrant on (careful not to overtorque). Then the Datsun cable fits like factory. You'll also need to get the throttle cable bracket from Redline or make your own

Rotation is from the point of view of the part, example, standing in front of the engine, it rotates clockwise. Standing in front of the carburetor (facing the throttle linkage side) the stock 1200 carby rotates anti-clockwise