For batteries: One pair GC-2 per 1,000 watts of inverter (Minimum recommendation) I have more than that for my 2KW inverter.
For converter.. With that much battery you really should upgrade the converter to battery line,k I have a Progressive Dynamics 9180 with charge wizard. Now I know how to use the Wizard and do so on rare occsions (the rest of the time it just sits there and operates in automatic mode)
A Progressive 9280 would be the equal to mine, Without dongle for most folks, WITH dongle for me.
I replaced the 9180 last Halloween it died after 12 years. Though the IOTA with IQ4, (I am told) is as good (they say).. I have yet to find a better converter in 12 years of searching, Well almost 13 years. OH Progressivew Dynamics products are MADE IN MICHIGAN USA. (Marshall, Insustrial and old US-27) Been there..... Where I got my replacement.