Funny you should ask this question.
I am currently in the final stages of fitting a barreled Siamese Mauser action to a stock blank. The choice was between using a 90% inletted commercial M'98 Mauser stock or making one from scratch. The Siamese Mauser action magazine box is about 1/4" deeper than the '98 action. That would require a pre-inletted stock with lots of "meat" to allow inletting to fit the siamese mauser action. Although the '98 pre-inletted stock is close, there were a couple spots around the tang that would need Acraglas filler.
I decided to start from a raw stock blank instead. It's a LOT more work, or course, but satisfying to get to the point where it actually LOOKS and FEELS like a custom stock. You might consider this as well.
For pre-inletted shaped stocks, try Richard's Microfit in Sun Valley, California. The have a website for ordering and product support.
HTH
John