I'm building a somewhat smaller scale system than you. I have 36 280Ah cells on order (semi-delivered, in the hands of my freight forwarder now) from Amy at Docan, planning to build a 16S2P battery, figuring ~22kWh+ available (N.B. kW is a measure of instantaneous power, kWh, with a time component, is a measure stored/consumed energy). While I expect to receive all perfect cells, shipping is sufficiently difficult where I am that I wanted a couple extra, but 2 cells having little to no use, I went for four extra and bought a 4S BMS, figuring I could find a use for a 12V battery.
With your quantity, depending on your timing, you might think about ordering from Docan (or one or two other known good stores) shipped direct from China. Even for my 36 cells and paying the significant shipping that came out noticeably cheaper. More cells will tilt the balance even more strongly that way.
As for which cells to get, probably might as well go with at least 280Ah cells, but larger ones may make sense. Might be able to save a string with larger ones, but cost is likely to be six to one, half a dozen the other.
You can get one or a couple of the expensive BMSs like REC, Batrium, or Orion and set them up in one or two batteries in (3|6)P16S configuration, or, what I'd probably think towards, using several JK or JBD MOSFET BMSs and do 16S(4|5|6)P. The latter means each cell is individually monitored, and, in the event of a failure, means less of your system goes down while you find, troubleshoot, and repair the issue.