question about v6 caliper brake upgrade?

[alteredraptor]

thanks to the great info from here, I was able to pick up a mc from a 95 runner frok my local yard for 20 bucks. thanks for the info and help

 

[Robkeith]

i found a few threads about swappin in bigger calipers and a bigger master cylinder for a better brake pedal feel. i have plans on doing that to my truck, i already have a set of calipers, i just need a master cylinder. my question is, since there seems to be more than just one option, which master cylinder should i go for? i found these two Master Cylinder | Marlin Crawler, Inc. but i dont know the difference in them besides the price, so if some one can offer some insight that would be great. thanks ahead of time.

Can anyone here tell me the differences between s13wb and s13wa calipers?