Coil question

For many good reasons, the secondary (hi-voltage) circuits were kept as short as possible, and ON the engine.
One end of the coil's secondary is usually the case, and electrically, "wants" the see the best possible path back to the outside of the spark plugs.
This is ideally through a well grounded coil strap, bolted to the engine.
Any other mounting location should then be equipped with some kind of VERY
heavy ground wire from the coil case back to the block.
This wire will make radio interference like mad (unlike mounting to the block).
And the coil is noisy by nature, we just don't hear it when it's out with the engine. On sub-zero mornings such minor things make the difference in going
to work or not. Mopars start fine at -25f if you have a strong spark.
This probably is never a concern for you, but it's why the factory wirings
were set up as they were.

Oh, and if that's the epoxy coil, it's noiser cause it's a solid, not a liquid for heat dissapation.
Oil was picked as the standard a long time ago, because in addition to carrying heat away from wiring very well, it also damped sound of the coil.