Master Cylinder Quesion

[62 mark]

I have fitted a hydraboost from a 99 Silverado in my 62 C-10 I am running front disk ,rear drum,and the donor truck was the same..I am at the point now where I am running brake lines, making them all myself..not as bad as I thought it would be. I want to use the master that came with the unit,so here is the question,which is not so obvious to me- What port is what as far as front-rear brakes? The front port is the larger of the two. thanks for any help!