I have tried to keep limas with cichlids and it just has not worked. Even though they are predatory, limas have trouble defending themselves vs territorial cichlids. My JD's and convicts beat up my lima pretty good in my 120. They were much quicker to get the food too, I almost had to drop food right in front of the limas face for it to get anything.
However, you do have a 125 and if it is 6' then there might be enough space. It would be an experimental thing for you, just have an extra tank available for the lima just in case.