Disc brake upgrade questions

[agnes the dog]

My research has left me pretty much blind and without a real definitive answer. I'm considering upgrading to front disc brakes, but I'm not really all that interested in power brakes. I've come up with several options. Before I make a decision, I would like to hear from others about their choices and experiences. If you have upgraded, please chime in with your experiences, good or bad, and any advice you might give....

Here's what I'm considering:

1. Purchase just the brackets and piece together the calipers, rotors, etc from parts stores or junk yards. Benefit - cheap. $100 +/- for the brackets, plus cost of the rest of the parts.

2. Purchase a kit with everything. Benefit - everything's in one nice bundle. Pricey, but maybe worth it if piecing together new stuff is comparable. $350 +/-

3. Break down and buy the power brakes. I'm not convinced that I need them. Very expensive and somewhat more involved than straight disc brakes. $650 +/-

A couple of additional questions:

What years do the kits pull the calipers, rotors, pads, etc from?

Do I need a new master cylinder? The one I have is about two years old and works fine.

I can see that I need a proportioning valve. What is it and what does it do?

Any suggestions about how to fit disc brakes on the stock rear axle would be appreciated too.

Thanks in advance.

1959 3100 dropped straight axle

JJ