All Terrain was never offered in short action.
OP rifle is a correct early SA classic stainless. The 22-250, 243, and 308 from the initial run all came with a fw contour barrel and were housed in the same Tupperware stock as the LA sporter contours … they just moved the action screws and adjusted the box confines.
I want to say this is all correct. Furthermore: The All terrain rifles were only made from 1996-1998 and also had the schnabel forend tip. If I'm not mistaken. This rifle in the OP is not an All Terrain model, from what I can tell.
The OP's rifle is just a classic stainless synthetic, fwt 22-250. I personally would stiffen up the tupperware, add a little paint and maybe a red pachmary, glass bedding and hunt the thing. Or go with a correct short action walnut stock. Some examples:
The stock on this rifle would work. It's from a 1984 short action fwt 22-250. Not for sale though!!
Example:
Stainless classic fwt. They always look great in a walnut stock^^
Or work with what you have:
I actually like the tupperware stocks. They are easy to work with.
After looking at the op's pics, I'd pull that damn rail off and put a good set of 2 piece mounts on it. Like the ones shown above. It's a fwt, not a precision rifle.