A friend of mine that's cleaning out his basement just brought me an ElectroVoice 664 mic that probably will work once I shine it up. It looks like it has a coax connector on it, of all things, so I'm wondering - how could I get it connected to a Kenwood TS-820 or a Yaesu FT -757GX? This thing is retro sharp.
I love old microphones and have a small collection of them. My favorites are the Astatic 10DA and the DN-HZ which is similar to the 10DA but bigger and more "retro". I am also partial to the Shure 444 which is really ugly but a great performer on SSB. My oldest mic is a collector quality Shure 70H which is beyond retro and made I think in the 1930's. I do not have any EV's.
I
hate to wire up mics, my eyes just ain't like it used to be and those
tiny 8 pin mic connectors are really nasty for me to solder. So I do it the easy way. I buy the mic cord with the connector already on it. The other end has bare wires to solder to the mic. This is an old Hams way of doing things.

You need to make sure the mic has the correct impedance for your radio. Low or high impedance and some mics have a switch on the bottom to change impedance. Most modern rigs use low impedance mics and a lot of oldie mics were high Impedance mics.
Note that not all old mics have PTT buttons and some that did are really poor. Get out your rig manuals and see what mic connector you need, there are 2,4, or 8pin connectors. Then Get the wiring diagram for the rig's mic input. Heat up the soldering iron and go for it.
Since you are a newbie Ham I would just make friends with a local ham that has good eyesight and is not to old and beg him to "show me how". You will save yourself much frustration.

Stan K9IUQ