1972 Front Disc Brake Conversion

I’m actually a bit torn. I have full KH brake systems for my project but as mentioned all of them are SBP. I have original BBP rallies in both 6.5 width and 7 width. I’m going for an original look. So even the SBP rallies would work. I even found a pair of BBP rear drums that look like the “darth Vader” drum that fits the 1 3/4 rear brake.
I guess in the end as for brakes the 73-76 disc is the most cost effective and most likely the smarter choice for all the reasons you mentioned. And for the OP it is actually the best choice. Put the 73-76 discs on and parts are very easy to get. You can even get new upper control arms.
The engineer in me wants to build something a bit more unique.