It was a hard time finding measurements of the B747-400. I did not succeed to find the exact measurements. By using many photos on internet, I was able to get a few references of sizes in the cockpit. I worked it out myself, and the results of measurements I used are shown in the diagrams below. Note that these measurements are an approximation of the real 'Big' one! The result seems very realistic when putting all parts together.
Throttle Quadrant
Forward Instruments
I have build the construction out of wood, and panels are made from plexiglass. All measurments are based on the panelsizes!