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A long time ago I purchased a Baer Big Brake upgrade for a Trans Am. The kit was not too expensive and really worked well. Years later, I needed new rotors and the Baer price was CRAZY. With a little research and some effort I learned that the Baer kit was made up of OEM C-5 Corvette parts and so I got pads and rotors for reasonable money.
I would suggest that rather than sourcing and building your own kit from pieces, go and purchase a brake upgrade from one of the non-wilwood vendors...maybe even Baer. This will get you matched and tested component combinations that would likely perform just as well as the stuff you're looking at now.
Here's an example:
https://baer.com/1960-1987-C-10-C10-pickup-GMC-Brakes/
EDIT: Not dissing Wilwood at all, just figure the OP isn't into spending that much.
-Kevin