With Passover coming up in a week, I'd rather not be gentile (rimshot, please)....
But about the BBD.....replacements for an SAD512D are going to be hard to find, and pricey. You will be looking for an R5106, which is a pin-for-pin replacement.
As a sidenote, there were two types of SAD512 chips. One of them was actually an SAD1024, used as a 512-stage BBD, with only one half of the chip functional. The other type is that used in the DOD 670, which is an 8-pin chip that includes a built-in flip-flop to turn a single high-frequency clock input into a two-phase clock.