Before you get too far along, you need to determine if the engine has needle bearings or ball bearings for the main bearings on the crank. Needle bearing engines are not usable for model purposes because they lack the ability to handle the thrust loads imparted by the prop.

The rest of your assumptions are correct. However, I doubt you will be able to flip the prop fast enough to produce a strong enough spark to start the engine. You will have to use a electric starter.

Good luck,

Jim