Saeed doesn't like links to other auction site so I'm just posting the information.

On EBay there is a new, old stock Winchester model 70 Super express stock for a 375 H&H for sale. The buy it now price is $189.00

I already have a spare stock so I'm just passing the information along.

There is also a factory custom shop, wood stock for a left handed M70 short action for sale at $145.

I searched Sporting Goods > Hunting > Gun Parts > Rifle > Left hand