Real deal or move along?

The link wouldn't open for me but here in the rust belt, if I found a CA-sourced 8-1/4 from an a-body I'd be all over it for 250 bucks. And don't assume it needs a complete rebuild but the brakes need to be Checked out.

I have a 225 64 Valiant with a 3-on-the-tree and the 3.23 7-1/4.

I don't know what your ultimate goal is for your car but personally I wouldn't be obsessed with 4 wheel discs. If you're road racing, maybe. If you're putting around with your slanty, no. Unless you're only doing it for status then that's up to you. (Chevy guys around here install gear drives just for the sound)

One thing to consider is the wheel change necessary for the BBP. More money but the wheel selection is MUCH better. If it was me I'd start sourcing parts to do the BBP 73-76 front disc brake conversion and drive the sucker.