c20 disk swap master cylinder

[paulbrgr9999]

I am reading in posts that the origional mater cylinder on my 1970 c20 can still be used after the swap (which we did this past weekend). All I need is a proportioning valve.

But when I look at the master cyliner on the 72 front end I bought it looks much larger than the master on the 1970.

So finally my question: can I use the old master off the 1970 or should I buy a brand new master with proportioning valve for the now 1972 front end?

I do have power brakes if that matters.