Man, are you in for a long winding road ahead of you!
I am a ship's engineer, now retired, and have been there, done that all my life.
My advice is, do the one thing, but also do the other.
so:
1) Learn to fly! Join a club and find out what it takes, and do it.
2) In the meanwhile, convert engines to your heart's liking
3) when confident at both, combine 1) and 2)

You will find out, that the short leaves from offshore duties will hardly be enough.