I checked the Interoperability matrix for your query.
SRM 6.0 & 6.1 only supports = 7-mode 8.2.x
For SRM 6.5 = ONTAP 9.1 onwards is required.
I think the recommended advise would be to : Move/Upgrade from 7-mode to ONTAP/cDOT. As you may be aware 7-mode OS code development is stopped, and full support will end 31-Dec-2020. It will be risk taking to run your enterprise application on 7-mode OS. Your Filer Model FAS8040 is good enough to run cDOT code so I guess it's just a matter of putting up a plan and go for ONTAP 9.x