Locos were known to change tenders and this certainly applies to this class (see above) What tender of what type was carried by a given loco at a given date requires a fair bit of scholarship to establish precisely.
The usual expedient would be to look at dated pictures of the loco if you can find any - try typing in name/number into google, unless you have some reference books on the class
I believe Hornby are offering versions of the Arthur with both 6 and 8 wheel tenders. Manufacturers have been known to make mistakes in this area and give a late crest loco a tender it lost while still in early crest , but in the first instance we would assume they've got it right. Perhaps someone can confirm that 736 was a South Western Division loco pre war ? - in which case the "water-cart" would be right I presume
The livery is pre war olive green, as used under Maunsell. The much brighter and more vivid SR malachite green was introduced by Bullied - I think from 1945, but Bullied took over in 1938. That would have been replaced by BR lined Brunswick green after 1948 , when the loco recieved a repaint. I don't think any Arthurs would have recieved mixed traffic lined black . However I'm an ER modern image modeller so SR steam scholarship is not my specialist subject
I assume in due course Hornby will ring the changes on all these liveries across all the varients of the loco. They are offering versions with 2 different cabs as well