The car does launch well.
Not trying to be argumentive but earlier you said you drove a 340 with 3.23’s in an auto. This is a manual trans discussion but feel free to give your stall and the gearing in the 904 or 727 or whatever automatic you used so we can compare those oranges to these apples.
You also drove a 73, 833, 3.23. Different car? Weight? Mix match of parts being it had a 3.23 in 1973. Should be a 3.21 so that’s Beggs the question, if it had a rearend swap did it have a 1973 gear set in the 833? Perhaps it was an early 3.09 gear set?
I never said it didn’t launch well and my definitions of how it accelerates shouldn’t have implied the problem was with the engine.