cam lobe question

[292farmer]

i was looking at a 1975 454v8 truck 4 sale and i read some manuals and all years except 75-76 list lobe lift at .2343 intake and exh. but 75-76 was .2590 intake and exh. yet their was no power increase, no change in compression why were these two years different? or were they typos? at valve, thats like .042 extra lift i figured u see a difference. i thought maybe to make up for low flowing heads, any ideas why? its not a deal breaker i was just curios thanks