Have to disagree with you there Dan. The 428 CJ is way faster stock or modified as evidenced by road tests of the day and current NHRA Super Stock records. Mine is way faster than yours too, the '68 is easily 500 pounds lighter to boot.
The 429 CJ is more robust and less likely to grenade than a 428CJ in stock form.
That being said, the 429 CJ is a rare and desirable beast. I had a friend who bought a '71 429 CJ Mustang back in '73 while we were both high school sophomores. Absolutely the wrong car for that application! He still has the car but it went from being a 12,000 mile all original car to a race car in a few years. Currently it has a tunnel ram with a pair of 660's and the 3.50 open rear is now a 4.11 Detroit Locker.