hey regal, yeah it's a bit of a shit job but the end result is well worth it. I started wire-wheeling them to remove the stubborn dirt/rust then I followed it up with sandpaper going finer and finer. Lastly I used metal polish and a polishing wheel to get to the final results, very time consuming!
as for the engine, while disassembled I wire wheeled the head and cases, cleaned it with degreaser and shot it with the engine paint. the pics don't really do it justice. I'll try and detail the next steps more clearly, hoping to have this build done within next month.