Ted,

You could keep the cost down by reshaping the existing stock and possibly the fore-end.

Many years ago I had pre-war BSA BLE with a semi-pistol grip.

Grange Guns at Redditch converted it to a diamond section straight hand using the original butt stock and reshaping the trigger guard tang.

The fore end was already a splinter shape.

I was pleased with the result but sold it on ( for much more than it would make now) when given the Edwinson Green BLE that has been my main gun ever since.