The box needs to be a "dead air" box, so the inlet should be the same size as the tube that passes through it with a simple pinhole in the box somewhere to stabilize air pressure. A tube still has to be added to the diaphragm cover if it does not already have one. The hole location is irrelevant on the carb plate as long as it's not internally blocked by some part of a gasket or diaphragm flange.

Another method is to attach a brass tube to the front of the carb that has it's opening in line with the carb venturi. Run a line from the diaphragm cover to the tube on the face of the carb. There's some pictures of this arrangement on the Wild Hare site somewhere. It's similar to the manner that 3w uses for their engines.

The tube into the fuselage method provides inconsistent results.