My last batch of engines came with the starter, ring gear, alternator, radiator, fan, and water pump factory installed. This makes an engine much easier to "autostart" using a simple "brick" plc.
There are also electronic governors on Ebay made by Barber-Coleman that hold frequency within .25 of 1%. Barber -Coleman's governors have been bought out by Woodward Governor. I got mine for $200 complete with throttle actuator, control box, and magnetic pickup and am installing it on the 20/1 that will be pulling a 20 kw 3 phase ST head to run my shop, with 2 cnc lathes, a 20 x 100 engine lathe, 2 milling machines, a Miller 300 amp welder, 2 bandsaws, a 18" x 36" Gould & Eberhardt gear hobber, and assorted other machine tools.
This governor/actuator setup is like a modern version of the actuators used on the original Lister SOM generator sets.
Mike