Yeah I've had a few things on order that keep getting extended. It's one thing if they say it'll be in next week, totally different ball game if they say next month. Hopefully Napa comes through!
Yeah the problem is that those online application guides don't do very well with the A-body years where there were two bolt patterns. In '74 the slant-6 cars came standard with 4 wheel drums, which were 5x4". But the V8 cars came with disks standard up front, and those cars were 5x4.5". But disks were available as an option on the slant-6 cars too, so, you could have a slant 6 '74 Duster with the larger 5x4.5" bolt pattern brakes.
My '74 Duster started out the exact same way, a 225 slant 6 with a column shift 904 AND the front disk brake option, so it was 5x4.5" all around and used the bigger 10x2.5" rear drums. But if you put it into one of those application guides it spits out all the SBP, 5x4" brake stuff.
The part number you posted is for a 10x2.5" drum, if that's what came off it the 2947R's should fit.
