Rebuilding the whole brake system on the SSuperwagon.
Setting it up for Towing..
Any advantage converting the Rears to Disk?
Any differences in the manufacture of new Master Cylinders?
Any Advantage going with Wildwood Front Disks?
What is the Best Brand of Brake Fluid?
SS Wheels are they strong enough?
Using Nitto 255/17/50's Tires
Going to replace 2.56 with 3.08's
Install a 383 and keep 2.56's
Replacing KYB's with Gas Shocks..Probably Belstein.
If you know a better brand or set up please advise..
Here's my take:
1. rear disc: for your purposes, IF
you are staying with a larger (17") wheel, the WRDC kit, with a 13" Corvette Z51 rear rotor, is worth consideration--it will clear the Impala SS wheel. Using a standard Impala SS rear disc package would not be of any benefit over the existing drum setup, but going to the Corvette-based system (better rotor options) is going to provide better brake durability. The only drawback to this, for towing, is that the park brake (aka "emergency brake") is quite small, and is not really designed to STOP a car (not to mention your towing load--GVW over 10K lbs) in the event of a hydraulic system failure.
So, unless you think you must have discs for the rear, I recommend staying with drums, and just maintain the crap out of them. I am not certain about this, but I do not think the Fleetwood "commercial chassis" rear drums (11.15 x 2.75) can be bolted-on to a wagon rear axle, since the bearing sizes, backing plate flange pattern, and axle standoff measurements are probably not the same as the stock wagon's 11 x 2 brakes. IF the larger drum package DOES fit, it would be a plus worth considering.
2. master cylinders: OE replacements from ACDelco are perfectly satisfactory, and make for easy changeout. There are several sizing options available--not sure what wagon uses, but 1.125 (1-1/8") is common, used on Impala SS & most Caprice applications, and 1.25 (1-1/4") is available, from 9C1. The larger MC, with no other changes, makes for a "heavier" pedal (more pedal force for the same braking level), if you stay with the stock wagon brake pedal. You can change over to the Impala SS & 9C1 (94-96) pedal assembly and brake booster, which are designed to work together, to improve the pedal ratio and bring the pedal force required to achieve equivalent braking back to more "normal" levels.
Also, all 94-96 cars with ABS, regardless of model, used the same proportioning valve. Unless you go to a rear disc setup, I do not recommend installing the "stealth" mods to the combination valve without doing other things. I would consider it OK to plumb in a manual-adjust proportioning valve on the rear brakes (drums) in combination with the stealth mod.
3. Wilwood "discs"--are you referring to OE replacement calipers, or a "Big Brake" package, as offered by TCE? If you mean just replacement calipers, the D52 unit is the one viable choice, however, even with it's twin piston design, it offers less total piston area than the OE unit. Other than the weight difference, the Wilwood D52 is more about cosmetics than any advantage(s) over stock calipers, which are totally reliable when properly maintained.
Bottom line, the shortcomings of the stock system begin with the rotors, and putting a cool new caliper into the mix doesn't change that reality. Better to consider the HD12 rotors or a big-brake package, which will include a caliper change anyway.
4. Brake fluid - ditto MD's comments
5. Wheel strength - steel cop wheels are better, for 17's, good luck finding anything equivalent. Ditto on larger tires
6. Do not try to tow with 2.56 ratio--look at what GM used, 2.93 for LT1 cars and 3.23 for L05 cars, as minimums. Consider 3.42 ratio.
7. Bilstein is always a good choice--but also think about sway bars, by up-sizing the front (from 28mm to 30mm minimum) and adding a rear bar, which may also require a rear LCA change.