If you will decide that A300B4 is the right aircraft for you, my advise it to opt for a wetlease from one of Turkish operators rather than your own full operation with own airframe. It will be cheaper in most cases, if you will be able to get the wetlease approval from your Authorities. Turkish operators are bloody cheap.
As it was corretly mentioned by ALLDAYDELI DC10-30F is nowhere close to 80t. Good -30F can take ~73.5t at max structural, but more often you are full volume wise rather than weight wise. -30F is normally considered as 60-65t payload aircraft. Also DC10s have nothing to do with ETOPS and unlike A300 is it really a kind of longhaul freighter along with MD11 and B747.