i would assume that the size of the [table16] tables would just be half of the original tables that soundfiler creates.. so, if you have your [table16] objects indexed with integers (and i guess you do if you have 1400 of them), then you would just take the original array size, halve it, and then write that size into a seperate table of table sizes. 

ie, you have a table, lets call it [table arraysizes] of size 1400, and you write values for the size of each of your 1400 samples at the index point of each sample.  then when you want to play back a sample, you tell tabplay~ or tabread4~ or whatever to playback sample number x, and to get the size of that sample you just send a value of x to [tabread arraysizes]