Gunnie,
If the action is in fact a British 303 with the bushed fireing pin and small extractor you may be well ahead to bring it back as a 303. Many, if not, all of the SMLE barrels have the same threads as the ME meaning you can simply screw one in. Of course in real life it's not that simple but close, you may have to take some off the barrel shoulder so it indexes with the action then finish reamer the chamber to headspace and cut the extractor slots. Some how I'm thinking there may be a spare SMLE barrel laying around down there if you want to give it a try.
Best