Davis does suggest using an electric starter. ANY engine either glow or diesel should be hand turned before using the starter
it insures it is not hydro locked, on his conversions I have used both the flip and the starter . If you go to his site under customer reviews you can see mine under Martin Bender Irvine 53 conversion. The advantage of the starter is once the engine is set you are not running the compression down for a start and big readjustments for running after a few moments it is up to tempature of course prop and large changes in temp can effect and require a tweek, that morning it was about 50 degrees The hydrolock issue is more of an issue on the very small engines since you are dealing with very small cylinder
displacements thats why he has the little spring starters for the cox 049s and norvel 061s on my OS10s and TT10s davis conversions I use a 1/2 A starter a quick spin is an instant startup even my 06 and 09 PAWs martin