Greetings,
Whilst 1:25 should be enough time to connect (albeit slightly tight to be honest), I'd however suggest booking all segments with AZ or DL in order to avoid any unwanted surprise. Moreover, presuming that you'll be travelling with a luggage, you'll not have to collect it in FCO if flying with AZ or DL and that can save you quite a bit of time, also considering that luggage delivery in Rome can often prove to be rather tricky.
That said, you will have to clear customs and change Terminal (from T5 to T1) in any case.
Good luck and have great time in Italy.