Most engines-even Fords and GM like around 32 to 38 degrees of total timing (without vacuum advance).
Somehow the check the timing at idle came about cause the factory dampers were not mark past 15 degrees or so. But it really matters more the amount of total advance and how fast it come in. Could be 4000 rpms and up, could be as low as 2500 rpms--some race cars have the total amount of timing all in at 1500 rpms. The lower the rpm the faster the advance is said to be.
You need some mopar performance timing tape that is to stick to the damper to show the timing marks up to 50 degrees or so. But its always flies off for me so I just scribe a mark at 36 degrees and then guess the 2 or 4 degrees. White paint works great but scratch a line first while holding the tape even starting at the zero mark.
You can just measure the distance but I forgot the length
