master cylinder

[airbrusher]

hope someone can help me out , i am building a 72 c10 which was a 6 cylinder three speed column shift with manual disc brakes. I have converted it over to a 350- 350 with power discs, herein is my problem when i went to hook up my lines from the proportioning valve to the master cyl the fittings are not right they are basically reversed big hole on the front small hole on back my fittings are just the oppositte. a master from a 73 has the right fittings but wrong plunger depth so no go there. supposedly i have the right master has anyone run into this or have any idea? thank you!!