Good Luck with your project.

BTW: If you use the Compressed-air method, as the air enters the cylinder, it is likely going to push the piston down and the crankshaft turns. At TDC it may not, but I never bothered to try to turn the motor by hand/starter to achieve it.

You can either try to achieve TDC,...

or place the transmission "In-Gear" Parking-brake "On" and block the wheels. When you apply the compressed-air, your vehicle "may" try to move a bit...

or, you can leave the trans in "Neutral" and just allow the crankshaft to turn freely.