Okiezeke -
Parts are still available both new old stock Lister/Petter and Indian aftermarket, though the former may be a tad pricey and the latter of unknown quality. At the current price if it is a good runner that is a good buy if you need power.
As to missing parts - right angle switch bracket, but easy to make. Muffler, but you can see that. Compression release linkage, but I have seen some engines without from the factory, people run them that way. Rack selenoid, but this is used on engines set up for gen set operation, general purpose engines did not have them. And it looks like the safety shroud is missing from the aux shaft, but those things are a PITA, not needed if you plan on taking any power from that end.