Yet another master cylinder question

[slepysal]

Ok so I did do a search.....I wanted to install a dual circuit master cylinder on my 60. I have the slave cylinder worked out, so no problem there. I have a master cylinder off of a 70 Impala drum-drum,and need to get some reducers/adaptors (from royal brass ,thanks cheif)to fit the existing line ( that will feed the fronts) and new line that will tap into the rear.
I thought the hard lines that come of my original brake / clutch master were 3/16 ( 3/8 wrench), but no they are 1/4 " (7/16 wrench ). So I have to get and bend up some new lines.
This is were I'm confused ,will I run into any problems using bigger hard lines when I do my disc brake swap ? I wanted to install a dual feed master ( for drums ) now , and swap in the disc master cylinder when I do the disc swap . The porportioning valve that i got from CPP has a 1/4 rear port and 3/16 front ports, so can I just use an adaptor to use the 1/4 front line ?
I know this shouldnt be that hard so thanks in addvance .