SRT8CUDA Build
Jim,
Dot sure if you ever got back to your replacement tail light upgrade but I have run across these "Plasma" LED 1157 Bulb replacements sold by West Coast Classic Cougar. They obviously are not just for Ford products and seem to be a quality unit with high lumens. They also offer a discount for larger quantities if you need to do several vehicles. Here's the link:
Plasma LED - RED - Two Pack Replacement 1157 Bulbs - New ~ 1967 -1973 Mercury Cougar / 1967 - 1973 Ford Mustang
Please let me know what you think! I love your 'cude build also! Great work!