Are the changes you're making to Alien Breed's code, or to your conversion layer's code?
I have to make some changes to Alien Breed's code, as it uses lcd ports at times, and some things are different, such as saferam areas and such. But that is really just about it. For example, I replace bcall(_grfbufcpy) with UpdateScreen, and bcall(_clrgrfbuf) with a routine that does the same thing to plottsscreen. Also, I removed things that included contrast setting, which I'm going to mess around with later. Honestly, it is really just changing address and bcalls, and altering lcd specific code.