Installing a new Brake Mster Cylnder

Seen a couple of the post where people had problems and installed new ones but I have a couple questions. Do I need to order anything but the master cylinder when doing the replacement? Someone mentioned that the pushrod be the same length, how would I know this? Is it obvious when I get the new one and old off the car side by side, or something I should look for when buying? I googled the part and shopped a bit but saw nothing on pushrod length while shopping.

The problem with the '87 B2000 is that it has very soft brakes and wont bleed out after I replace the Brake lines. The brakes work but I wouldn't want to have to stop quick, I usually leave distance and pump to stop signs or down hills. The car has 72k original miles and the pads look good.

I appreciate any info you can give.

Thanks!

Just buy a new master cylinder, be sure to follow the bench bleeding instructions,and use the old push rod,bleed all yor wheels,starting with your rear left wheel,..

Measure the depth of the recess on the existing MC. Then measure on the new MC. If they're different, adjust the pushrod by that amount.