I also wanted to be as faithful to the original Great Pyramid of Giza as I could. So I did some maths.
The PolyTrack car is same size as a pillar. An F1 car is 200 cm (2m) wide. 
The pillar fits into a block 10 times, which makes the block 20 m wide.
With the pyramid having a base of 230 m × 230 m, I used 11.5 blocks for the base plane.
The height of the pyramid is unfortunately not accurate, since PolyTrack doesn't have blocks that create the correct slope.