I did a '73 disc conversion on my drum brake small ball joint '73 swinger. It got big ball joint upper control arms knuckles, etc. Re-bushed and used old lower control arms. Used a 73 disc type prop valve.

Price was similar. More work to swap. Similar stopping power. The trade off in brake part cheapness and availability with the '72 knuckles and chevy brake parts is offset by the high price of '72 suspension parts, especially lower ball joints. I guess a brake rebuild/ freshen up is more frequent service than a suspension rebuild, but the '73 suspension is way cheaper to rebuild.

6 of one half dozen of the other?

Kevin