Hi again
A few discrepancies here - Northern Rhodesia? Tanganyika, 757?
Speebrake lever is captains side of the centre console.
I would not even consider a single engine takeoff anywhere irrespective of external influences you just wouldn't do it.
Depending on departure airfield, Zimbabwe has Migs Shenyangs & hawks, DRof Congo has a few Migs I believe, Zambia likewise, Malawi nothing, not too sure about Kenya or Ethiopia. Certainly I would not expect any of them to be able to react quickly enough to enable an interception but I may be wrong.
Regards
GG