Car dies in gear...

A 300 rpm drop, with tires rolling speaks to a major torque loss, or the tranny is trying to get two gears at once.
Stepping on the brake and engine stalls, speaks to a major torque loss, or a vacuum leak inside the booster,clamp the hose, and try it again.
With your T-port now synced and 800rpm at idle, your timing looks to be right where it needs to be.

What does the vacuum gauge say during all this?
Have you done a compression test?