My memory is getting a little fuzzy, but I think the 727-100
had a higher Vmo at sea level than the -200.
Might dig out the old books and check it.
The A-B switch on the 727-200B model I believe were
required to be in mode B at ZFW above 136,000 lbs or
TOW above 172,000 lbs. This would lower the Vmo to 350KIAS
at sea level and 372KIAS at 26,500 ft.
Mmo remained the same at Mach .90