itsafox: Does this version of SW have native monitor resolutions (like the GOG version of Blood), or is it limited to the cruddy 800x600 (I think) max resolution of the original?
You can get higher resolutions, up to 1280x1024 in my experience by using a "cheatcode" to cycle them.
Press the key you have bound to "message/talk" (for me it's 'T'), type
swres, and hit "Enter". Better do it in windowed mode just in case. It will cycle through a whole bunch of resolutions, including some very weird ones.
You can also directly put the resolution you want into SW.CFG (in the SW Complete installation directory.) This is NOT one of the .conf files from DOSBox. If it's one of the supported by the game resolutions, it should work.
example:
ScreenMode = 1
ScreenWidth = 1280
ScreenHeight = 1024
Make sure the DOSBox resolution (through GOG's graphics setup utility) is not any smaller than the one you choose. I'd also recommend setting output=openglnb.