Back to basics, dudes!

All you really need is a piston stop, a pencil and a tape measure. You do not need to have degreed in the cam. That's a topic for another instruction.

Install the piston stop Turn the crank until piston runs into stop. With the pencil mark where the pointer is pointing. Now turn the engine around the other way until you run into the piston stop. Mark where the pointer is pointing. Now use the tape measure to measure between the two marks. Calculate exactly half the distance. The halfway point between your two marks is TDC. I'm hoping your Zero mark is halfway between those two marks.

Piston stop? Strap metal, three holes, three bolts and two nuts. You can make it for very little $. No need for anything fancier than this.

R.