All 8x10, 5x7 and 4x5 backs from different brands look very similar, no much difference. Make sure the “T distance” on your film holders is the same...
Reduced backs from Kodak/Graflex/Century would fit in your camera better. The reduced backs from Burke & James, Deardorff may also fit in your camera...
I don't know when this usage became common, but as others have said, it probably goes all the way back to early plate photography when exposure times...
You may buy any kinds of 5x7 and 4x5 reduced backs to use on your camera with little modification or without any modifications. Probably the reduced...