Hi ,
You can use Transport Connection to identify the different Objects which are not migrated .
Goto RSA1 --> Transport Connection here you will find all the Objects and with the 4 digit Object Type you can identify what has been migrated and what has not. For Example Data source with type RSDS is for 7.0 and the one with ISFS is for 3.5 .
Hope it helps.
Regards
Kamal