Oldpilot: Assuming that your linking schema is done correctly, yes. I've used this a number of ways; I've D&D'd html files; I've D&D'd ePUBs, and I've D&D'd OPF files. All work. ;-) I started out way back using the OPF for KG, when I graduated from ye olden MBPC to mobi, (because when I first started, I'd explode an ePUB and then double-click the OPF to launch MBPC, it feels like eons ago), and, honestly, I forget how I even stumbled on it, but yup, it works.
OTOH, you could just stick with Previewer, which has a number of advantages as well.