Boyd's at one discovery convert to a marauder gen 2 stock

You will have to enlarge the slot for the airtube since the Marauder's is a larger diameter. Last time I looked Boyd's had a stock inlet for the Marauder, but not in the slim stock pattern you can get for the Discovery. Not sure about the trigger or mounting bolt. Best way to start would be to set the two actions side by side and look at how the dimensions compare or tray to fit the action into the stock, that should give you an idea of what's involved.

I can't speak to the modification necessary to go from DISCO to MROD, however I did recently lay hands on a Boyds At-One stock and was pretty disappointed. It is cheap, which it has that going for it, but the finish isn't very nice (kinda thick and slightly cloudy polyurethane with the odd bubble and it doesn't really bring the life out in the wood), the grip needed to be replaced as the factory one was way too square and hard-edged to fit a human hand (who designed that anyway?), and finally the cheek riser had very little adjustment so I had to entirely rebuild it to get enough lift to see through the scope. With that done I should add, it means (on a bolt action rifle) I had to fully remove the cheek riser in order to remove the bolt. 

There were other problems with it as well regarding tolerances and inletting, specific to the installation of a firearm action which also frosted my cake while working on it. 

All in all I guess I'd say that, while it was relatively cheap, I'd have rather paid more and gotten more for it. I should also add that, if you do have to increase the tube diameter on the stock, that can be a very slow and painstaking process if you don't have the specific tools. And if you have to increase it anyway, you also may as well start with a nicer stock. 

Just my opinion on the matter though. I hope it is helpful so you can at least have a clear idea of what you're getting. In this case, the pictures A) don't show the fact that it took me over two days of sold work to get that action and bottom metal into the stock and B) doesn't show just how the finish sucks the life out of the wood.