Resistor Spark Plugs, Wires or Both?

Depends on if the radio still makes noise, LOL

Start with supressor wires. If they aren't enough go to plugs

Also understand, this is not the entire answer. Sometimes noise is radiated by the wiring, especially in modified wiring. That is to say, the OEM spent a lot of time "getting it right" and "we" come along and change it

"What helps" is bonding straps, min. of two from the rear of the hood to the firewall

Grounding clip / springs for the same reason under the hood. These are add on "electrial contacts" which "bite" into the hood and ground it. Used in two way radio

Lead / harness dress. Since "everything" for an MSD is under the hood except the small red trigger wire, you might put a bypass capacitor on the small red

"Lead dress" means running wiring so it helps suppression. Don't run high current pulse stuff like the two coil wires for your MSD next to other harnesses. DO run it as close as possible to the firewall and / or block to provide a ground-plane type shield.

DO NOT put a radio supression cap on the coil positive (with MSD) and DO NOT hook a tach up there

If you have a tach, try unhooking it and see if it drops the noise.