Hello Sekhar,
have you already activated the business functions FIN_TRM_LR_FI_AN (EhP3), and FIN_TRM_LR_FI_AN_2 (EhP4), FIN_TRM_LR_FI_AN_3 (EhP5), via Tcode: SFW5 ?
Afterwards, the migration category 6 "Conversion from >= Enterprise 2.0 and <= ERP 6.0"should be available.
Best regards,
Jasmine