One good hint: take a look around.
Do you think that you are more smart than anyone else who missed this "perfect" aircraft? Why do you think almost no one operating 1011F and Belgian/Monaco guys have no success in promoting it (apart from his personal character)?
Marc's birds are 56t max gross payload I believe (52t nett). With this payload it can fly for ~5:30 and still have a legal reserves.
Maintenance is rather expensive if you want to maintain a reasonable dispatch reliability.
If you are approaching this outfit, be sure to count your fingers after every handshake.
Personally I know only one way to make a money from Tristar: buy a passenger aicraft cheap but with reasonable amount of hours remaining, strip it out, register in Africa and fly the bulk cargo as long as engines are running. When it stops, buy the next one. It works.