Possible solution : rewrite it completely.
This is the AROS way but it is slower than AOS3.x on same hardware. A rewrite in asm, on the contrary, would be faster than the original.
Program after program, rom library after rom library, it is time consuming and a daunting task, but nevertheless doable.
Now who can and is willing to do it, is another story.
Well. Give me enough money to pay my bills for several years and i'll do it