No special courses actually required
Assuming no AOC involvement, inc a management company with FOM, then there might / should be no extra cost (s) or training required.
When you next do a recurrent, ensure that the FTO is asked for PIC check, and not SIC.
Mostly you can get the check ride in the LHS, and the PIC check ride, which is a few more exercises, but if you are with a reputable operator, and or a reputable FTO, you should with 100 hrs on type breeeze the ride.
I am in the sim more than average pilots, and many times the student seeks a PIC ride, and he gets it. Licence rating endorsed accordingly.
It is up to an operator if you are employed LHS or RHS.
Re the 25 line sectors, this is an insurance requirement usually. But you have the sectors as SIC, so should not be a problem.
Might need 3 or 4 T/O landing in LHS in real aircraft to actually exercise your PIC rating.
Go for it......