Except if you need heatsinking the BD139, there shouldn't be any problem in using other transistors like the 2SC3298. It would only be a question of reversing the pins insertion, leaving the metal tab towards the other side.
To check on the pins you can use a DVM, though it's troublesome. Those having hfE meters would simplify the job.
I couldn't check on the MJE340 pins though.
The TIP types might be noisy on some positions.
On the low current types, usually having the base pin in the middle, it would only be a question of reversing the body.
Going for larger bandwidth types maybe a good thing.
In any case, Mouser does stock some European types, like the BC559 and BC550. The BD139 is not listed, but the 2SC3298 and MJE340 are.
At least this shouldn't stop you from going on with your project. What project is that?
Carlos