Depending on who wrote the game on the ST decides if its easy to translate to Amiga without much fucking about.
If its ST only, then its harder because it was solely coded for that machine.
If it was a conversion that was done for ST and Amiga, the code for the most part is structured the same in both versions, with different subroutines for graphics and sounds.
Its not impossible, but is there an ST hardware reference manual on the net?
Or, does anyone want to try and contact the programmer of Sundog..... never know, might still have his code!