Car stumbling and dying

[DRJDVM's '69]

Big problems now....****..

Did the vaccum guage and it peaked around 1-1.5 turns out.... car seems to run better too..... did it a couple of times and messed with the idle.

Took the car out for a ride and it seemed to run better. Went on the freeway, got on it alittle to pass someone, then started to cruise at about 70 MPH and 2000 RPMs in 5th gear....went about 3/4 mile just cruising and ....bamm, some black smoke.... car just started to die and I had to pull over on the side of the freeway.... car cranks but no oil pressure....WTF....

called AAA and the car is home....

WTF did I do ??? How could I have broken something cruising at 70 MPH..... I did get on it alittle before but it seemed fine and nothing went wrong for almost a mile..... the motor is all forged, Dart block etc etc, so....

Could I have leaned it out too much and got into detonation ??

Not good....