It looks like a great project, entirely restorable. You might have a decent bore there. Unless it was fired with corrosive primed ammunition and left to rot, you have a good chance of actually finding lands and grooves. Its funny how often I've gotten rusty old rifles like your SMLE (and worse!) but with a nice bore under the crud. That rust will come right off with 0000 steel wool and oil or solvent. I have always had success with Hoppe's no.9 solvent. The advice about the screws and using a liquid wood stripper is right on. NO sandpaper on that stock, please! Best of luck!