brake issues?

first let me tell you about my set up. i have a 14 bolt rear from a 79 chevy with drum brakes and a ford dana 44 with twin piston calipers and a stock 88 xj master cylinder. once i got it all put together i had a real soft brake pedal. a body of mine did the same swap excapt he has a 60 rear with discs when he changed his proportioning valve to a zj his brakes worked great. will this work for me even though i am still running rear drums or do i need a bigger master cylinder, if so does anybody know one that will work? appreciate the help. and also have a baby coming in a month so my budget is pretty much non exsistant.

You need to push more volume.

There is an e350 master cylinder that will bolt to your existing power booster, and its pretty cheap. I'm not sure of the year, search here.