But now I had the idea, to publish the scores of these arrangements through some sheet music publisher. This might be the point, where I have to get the permission from the original author or from whoever now owns the rights of the composition. I guess, most of the software houses from those days are no longer around. And how do I contact Rob Hubbards...?

Does anybody know the exact legal situation?
Any suggestions, what I can do?
Greetings & thanks in advance,
Markus