After consulting with Larry Christensen (well known 1st Gen Camaro restoration specialist), the self-tapping "RBW" 1/4-20 x 1/2" self-tapping screw is a common screw for this application, and considered correct for judging purposes. A very close RBW screw alternative is available from Paragon Corvette Reproductions, Kit #11189K, for about $5. The screws in this kit are not self tapping but a good alternative.
JohnZ...is your original screw for this application still on your 69?
Does anyone else out there have a survivor 69 with the original screw or wire tie strap still intact? If so, please post a picture and let use know the build date and VIN on your car, to give us an idea on the assembly time frame of your car.
Many cars have this original screw missing or replaced due to the frequency of removal for belt and/or alternator replacements over the years, or due to the threads in the bracket becoming striped.
Thanks,
Dave