You can flow right through the mechanical pump. I am not sure where the best place to drill is. If it is a circular pump, you can 1/2-a$$ it by hose-clamping it to a frame rail. It's temporary, right?

Also, do not assume that gas is not getting TO the carb. The fact that gas isn't going THROUGH it is more apparent.

If the main jets are clogged, pluged or otherwise obstructed, no gas will flow through the carb except on the secondary side.