If I was planning on bedding the stock later, it sure would be handy to have the selector hole "plugged"....
There are lots of ways to "fill the gap" none of which are very difficult. The most expensive is to buy a fake FA selector sw, the cheapest is to do nothing....
The area that will likely need to be filled for a Chinese rifle would be the area relieved in the stock for the front of the disconnector transfer bar..... Nork rifles need that spot filled as the connector pin is flush with the receiver. So you could have troubles if you don't at least do the "Popsicle stick" mod....
Personally, I prefer to use a filler that binds permanently to the stock ie: devcon.
If I get ambitious, I may post some pics later of a USGI stock I am currently working on.....