The mountlist you've written is correct compared to the WB 1.3 mountlist in SYS:Devs other than that specifies DF2: rather than DF1: as you have. 40 tracks would be 440k I assume.
Something I didn't know was, until reading online, the A1020 doesn't support diskchange detection so when removing a disk and inserting another you need to type in CLI "DiskChange DF2:" after changing disks.
Another point shown online is REMOVE DF1: could be needed first if DF1: is auto-mounted at boot for a 880k drive?