Cab, I have never read that "rev limiter" thing. I bought my orange DC box in 1984. I think it has more to do with a slightly faulty memory and the Direct Connection/MP catalog wording that says it's best used up to 6000rpm. I don't think there's enough electronics in the box to include a rev limiter, unless the transistor speed isn't fast enough for more than 6000rpm.

OP, there are two reasons why your cam is acting like it's too big. First of all you closed up the lash and that has the effect of increasing duration. Then you are running 1.6 rockers and they have the effect of increasing duration. BTW your lifts with the 1.6 rockers are 0.657 and 0.661.

Also, your rear gear is really slowing you down off the line. Those are highway gears with the big tires. I think you need 4.30s. Now it seems you're crossing the line at 5000 rpm.

AndyF was right, the cam is too big for the car and gears. 4200+ lb and 3.54s don't work with that cam. If you want to keep the car and gears the way they are, then the cam has to change.
If you change the gears and stop making the cam act larger than its measurements, the cam can stay. I'd run the test with 0.022" lash. Most sources say that 0.004 more lash won't hurt and the stock lash is 0.018. I'd be in favor of keeping the cam as you've got it broken in.

One more thing: If you are showing no vacuum under the carb as you cross the line, the carb doesn't need to be any larger. As you change the gearing and start going faster, it may happen that you need more carb. But that's for later.

R.