Many of the guys I race boats with use Sullivan starters, I personally have two of them and have had them for years.
For engines of .46 and under, I would recommend the high torque 600/601. I know Sullivan says it will start up to a 1.2 BUT personal experience doesn't support it as my 601 struggles with a .67 marine engine unless I have a fresh, fully charged battery. Sullivan doesn't say anything about using anything over 12VDC
For larger engines, you would probably be able to use the Dynatron 603. Sullivan says it will handle up to a 2.4, which I tend to believe. At 12 VDC, it has 50% more torque than the 600/601 and, if that won't cut it, the Dynatron can handle 24VDC and give three times the torque of the 600/601. You can order direct from Sullivan and, depending on the spinner on your plane, you can order the optional spinner size compatible inserts for the starter shown on pages 26 and 27 under the "shop" link at the top of their home page. Their website link is
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Sullivan – Premium Radio Control parts for planes, drones, cars, trucks, boats and helis (sullivanproducts.com)