As has been asked, WHAT engine parts are missing? This would make a major difference in complexity/cost.
Also, don't know if you've done vehicle restoration projects previously. If so, you know what to expect; if not, frankly, unless you are prepared to spend a lot more money than you think you will need to spend AND you are prepared for it to take much longer than you think it will, it's much more cost effective and efficient to buy a Commando that is currently in good, rideable condition rather that taking on a restoration project. Frankly, I know of more such projects that ended up not being finished at all and resold than ones that actually ended up with a "restored" vehicle.