[Heathkit] D-104 for DX-100 crystal or dynamic and what impedance?

[Howie WA3MCK]

Group,

I'm preparing to put my old (but refurbished) DX-100 on the air as soon as
possible.
I do not have a microphone but I do remember that almost EVERYONE utilized
an Astatic D-104.

What I don't remember is:
1.  What element is preferable? Crystal or dynamic, and
2. What impedance should I go with?

It's been about 40 years since I've had her on the air and I have forgotten
quite a bit about this rig.

For the past five or six years I've had my highly modified (600 ohm
balanced audio input) DX-60 on AM with a fancy studio mike, processor, and
other embellishments.

Recommendations, advice, and references solicited.

73 de Howie WA3MCK