well, AFAIK there is no way to convert busy data for tally. I am saying this bcoz both software coded in different platform. New version of Busy are developed in Visual Basic 6.0 + ADODB connection with MS access database & anceint version were in C++.
Same thing again older version of tally were also developed in C++ but newer are unknown to me but I am sure it not developed in C++, .Net, or VB 6.0 it may in delphi or something like this.
So, forget about data conversion. It is impossible.
Other hand importing data from 5.4 to 7.2 just copy paste all contents of the data folder of 5.4 to tally 7.2 data folder. Tally will do all the required action, it will convert itself in it's compatiable database information. But remember don't overwrite any folder or file.
Before you do this back up all of your data, as many guys here have lost their data while upgrading Tally.