The only "shorty" plug for 75-79 Camaro with a 350 that I have been able to find is an Accel #0276S-4 on Summit
I have checked the NGK c/ref chart, and it's not there.
0276 (without the "S") crosses to a UR5 (one heat range colder than UR4)
I've copied the relevant pages and attempted to highlight the info from the NGK catalog. See attachment