The only 7+R shifter knob I could find was for the Corvette Stingray. The one listed on Amazon Canada sold out, so I ordered it through Amazon US.

DEWHEL Aluminum Black/Red Vintage Manual Shift Knob 7 Speed with Adapter Compatible with C7 Corvette https://www.amazon.com/dp/B09QZP4YRB/ref=cm_sw_r_awdo_C0B5JFZ3Q6QMM1KVY45Q