Hydroboost Prop valve Question

[72tutone]

Guys,
I scored a hydroboost off a 93 astro van over the weekend. I have a question within regards to the prop valve and master cylinder hookup

Which port on the master cylinder serves as the front brakes? I plan on using my original prop valve and I need to know which port goes to the port on the master cylinder. I would think the larger of the two reservoir would go to the front brakes and the smaller to the rear. Whats odd though it looks like the front of the master cylinder users 1/4 and the rear uses 3/16. So from that perspective I would think the larger would go to the rear as well. But its also using the front port which is the smaller of the two reservoir's

My setup is disc/drum factory.

Thanks all