Here we go again.
Yes Katana did vary in length, but just because modern martial arts practitioners use an item does not mean it is accurate contemporaneously with period use.
Katana size generally still fell between 2ft and 3ft; a practical length. The sword depicted just looks too long to me, more like the length used in the Nambokucho period (1333-91) when longer swords became fashionable (It looks more like a Katana/Tanto combination than Katana Wakizashi) In this period however, the sword would be a Tachi not a Katana. The sword in the model also has the Ishizuki sword furniture at the tip which was more common on Tachi and rare on Katana; this may have caused some confusion.
Kenshin does make a valid point about the tang, but generally the Tachi scabbard had fittings attached to it (similar to the Napoleonic Sabre scabbard) so that it could be hung (blade down) on horseback.
The use of Daisho (twinned swords - literally big/little) did not arise until the Muromachi period in the early 15th century. The use of Uchigatana (swords carried blade-up) which include the Katana and Wakizashi (companion sword) were also adopted in this era.
I would be interesed to see the reference used for this configuration of gear.
Why is he wearing the Wakidate on it's own? It would be useless in a battle and would probably draw scorn from other Samurai if worn in the street or for a duel (the use of a separate back-plate on later styles of armour was nicknamed "the coward plate" as only a coward would turn his back to the enemy). Touchy lot these samurai
The suspending cordage also seems to go under the Wakidate, rather than to the attachment points which would be on the outside.
Why does he appear to have half a Kyubi-No-ita sewn to his left sleeve? The left sleeve would be reinforced, but if armour was attached, it would fitted seperately at the top of the arm to protect the shoulder and body-armour cording and it would be laced on.
The Suneate (shin guards) at the time of the armour shown (Heian period 8th-12th cent) would be of three plate, wrap-around construction and Ox-hide "shoes" would be worn rather than straw/grass sandals.
As Oda said, what we have seem to have here is a 16th century Samurai wearing anachronistic Heian armour. No I can't say it never happened, but it's highly unlikely. We are talking about a 400 year old difference in a country where humidity would probably have taken a great toll on the preservation of such items. Would Sir Francis Drake have put on Crusader armour as first choice to go to fight club? The lack of shaved forehead also suggests that the model is even later than the 16th century - more likely the Edo period (17th cent) which makes things even worse.
But of course, I forgot. So many of you out there don't care, do You?