First up are 3 units of cavalry.
Crikey Martin, your really testing my maths skilz (of which I have none!). What a whopper of an entry. I'm really looking forward to seeing this army arrayed for battle at the end of the Challenge.
So Points wise... I concur with your calculation on the Cavalry and Infantry, but I think your selling yourself short on the Nellies. I'm scoring these as 112 points (7x8pts treating the elephants as Vehicles, plus 21 crew for 42 points and I'm adding another 14 for the hand decorated blankets, 1 per side). Finally the Chariot, I can't fault your logic on the points for these but I'm throwing in a couple extra because this must have been a beast to assemble!
If my mathmagics adds up that comes to a grand total of 386 points! Well done.