Will Spring-Loaded TDC Locator Tool Work on a Mopar Small Block?

Yes you can find the top of piston travel when the piston comes to the top using the center of the piston for degreeing the Cam. But not Top DEAD CENTER. Unless you already know the roll over of the crank. Piston at the top rotating counter clock wise is not Top Dead center. Top dead center is the midway point between when it reaches the top and when it starts going down. That is roll over, and the only way to get back to TDC is turn it backwards.

Is TDC needed to degree a cam ? No, but that is the accurate top dead center. Sometimes there could be 4 degrees of roll over . I do not use a piston stop method to degree a cam. But use a dial indicator on the center of the piston, So piston rock doesn't come into play.

So yes you can find the top of the stroke with a dial indicator faster . But don't say you found top dead center without turning it backwards.