Bendix gear clearance to ring gear

[oldguy64malibu]

Back again with another question.
I am installing rebuilt starter motor on a 1964 283, The installation instructions call for a specific clearance between the bendix gear teeth and the flywheel ring gear teeth. My question is how do you engage the bendix gear to the flywheel and hold it there while checking the clearance ? Am I having a senior moment and over thinking this ? Thanks again for your help. When done with car I will post a picture of it.