Steve is correct on ball joint sizes & applications. D52 pads are stock Caprice & Camaro pads – some say D61 pads will fit with the bigger rotors, but them you might need bigger calipers off a truck. That changes the hose end too (banjo bolt is bigger).
I’m doing the 12” brakes on the front of my 77 Z28 right now. I cheaped out on rotors for now as I am waaay over my budget. I got regular (not slotted) 1LE Wagner rotors from rockauto.com for about $43 each. That $120 or so bucks I saved can go towards some good pads + shoes, probably Porterfield R4S. Those 1LE rotors come with metric studs too, so you might need new lugs or need to replace the studs. The Napa part number for the studs is 641-1013. You need a 35/64ths drill bit to open the holes up.
I got the Howe ball joints for the lower arms. Did you buy the control arms yet? If not, check out
http://www.scandc.com/. Call & ask for Marcus. He knows those cars upside down.