Jerk and stall when put into gear?

We verified firing order and points dwell when we timed. Followed the book fairly close when timing ect. I'm fairly certain that the timing is set. The carb squirts perfect when you work the throttle so I'm positive it's getting fuel. I will def look at the kick down and do a leakdown test. It all seems to happen under a load. I will also throw the rear up on stands and see how it acts. Thanks for all the help and suggestions guys I haven't messed with anything this old in ages

-Jake