Hi Humayun,
I have also built a space shuttle. 1/72 scale - revell. looks good but the main mistake is that the area from the cockpit windows down to the nose is flat on this model . should be slightly curved like all the full sized craft. I purchased this model also from frontline hobbies in Newcastle.
you would have to contact them.
I have seen a few other brand kits, 1/72 scale floating around on the net for sale.
I am in the process of building a larger scale shuttle out of wood.I may use this to set up a mould to produce a few fibreglass shuttles somewhere down the track.1/72 scale is the biggest kit that you can buy.there are a few suppliers selling larger scales from the states but are already made up.. see SPACETOYS.COM for a start.
peter l