Something about this just doesn't sound like a motor problem. Are you sure that the smoke was acutally coming from the exhaust?? Or was there just a lot of smoke present?
Clutch pedal on the floor sounds like a broken clutch line. If the smoke was just present, and not coming out of the exhaust pipe, it could just be from clutch fluid hitting something hot. I'm no mechanic, and not as knowlegable as some of these guys on here, but I know a little bit. It just doesn't sound like an over rev, and sure doesn't sound like the motor let go.

 

my 2 cents,
thrust washer might have poped out, had the same problem; clutch sometime stick, movement of crank...... check out oil pan for washer?? hopfuly it 's not!!!
best of luck