Can someone take a Scummvm gog version of the game and run it in dosbox?
Depends on the game. ScummVM works like GZDoom (you just add the WAD files) - you just create a folder per game and add the relevant datafiles
then add the folder to ScummVM and it'll pull all the data from them completely bypassing the original .exe. The problem is, GOG have recently dumbed down their own installers by unnecessarily removing the .exe's from DOS games so you can no longer run them in DOSBox. However, if you still have the disc versions of the games (or re-acquire the relevant .exe's from "Abandonware" sites), then they should still run fine.
In some games fortunatelly the original content exists or it was added later. At least in my library Gabriel Knight Sins of the fathers has all the files, including the exe, intact.