I'm not familiar with that mic. The wires may not be the right size to fit an RJ connector, or the wire/insulation may not grip satisfactorily.
In any case, hand made connector typically are not strong nor flexibly rugged. After all they are intended to lay behind desks and in cableways with rare connect/disconnect cycles, and no tension.
I recommend cutting a factory made connector from a quality +stranded cable and splice it to the mic cable. Shrink tubing on the wires and two layers of single wall tubing or one of double wall (adhesive) tubing on the final splice would be wise.
Caution: If there is any chance the radio has a pin with voltage, typically eight or nine vdc, be absolutely certain of your pinouts, and continuity check everything! You only get one chance to short it out!