350 KVA HV Transformer? 3 phase calculation confusion

[santidreamer]

I need to buy a 3 phase HV transformer for an apartment block

1382 Amps is the total predicted single phase load after diversity.

1 Phase KW
1382 Amps
230 Volts ( I/V)
317.86 KW

KW 1 Phase KW to KVA

317.86 KW
0.9 Power factor ( KW x P.F. = KVA)
353 KVA

KVA Single Phase to 3 phase conversion
KW = V x I x 1.73/ 1,000
1382 Amps
Divide total load by 3 load per phase
460 Amps per phase
400V
1.73root 3
319 KW

3 Phase KW to KVA
318.KW
0.9Power Factor (KW x P.F. =KVA)
354.KVA

So 500KVA transformer. Needed