"I'm hoping there is someone out there who can point me to info about the quarter-mile splits in some of the older mile World Records, particularly, Gunder Hagg's 4:01.4 (4:01.3), Landy's 3:58.0 (3:57.9), and Elliott's 3:54.5. I've seen some data but doubt it's accuracy."
A book that EVERY, and I repeat EVERY track fan should have is the "IAAF Progression of World Best Performances and Official World Records." I cannot understand why T&FN has not (ever??) offered it; it is, however, available through the IAAF website. This books provides reams of information, such as:
Splits on Haegg's 4:01.4: 56.6, 61.9, 61.2, 61.6
Landy's 3:57.9: 58.5, 60.2, 58.5, 60.7
Elliott's 3:54.5: 56.4(!), 61.8, 61.0, 55.3(!).