If still small, it could work. Just make sure you have places she can fit and not him. To get a bit of peace time away from him. Cichlids take a go or few to get it down right. So don't expect sellable fry the first go.
75 is a better than a 55 to try this in due to it's 18in width rather than 12. But I wouldn't try if the fish are bigger than 8in. Getting to big for amount of space available.
When I got mine she was bigger around 4.5in and in a tank with male's. So probably made the eggs when with them. She would drop like 10, eat them over and over till all were gone.
I heard they grow 1" every 3-4 months, so with that slow growth rate I think I can squeeze a few spawns in so they can get the hang of it. I'll talk a bit with my lfs about GTs and if they're willing to give some credit beforehand.
I think I'll be able to breed them up until the male or female gets 7" going on 8", the male will be bought as a very small juvenile (2-3"), so my female will defo be bigger.
After they get too big to spawn in that 75, if I don't have a bigger tank, I'll try to keep them both. The female does have a lot of significance (from a friend that works at petco, it would be rude to get rid of his former pet.) but at the point where I can't breed them in a 75 I'll be attached to both male and female.
In summary, they'll get a 75 each, but they'll breed in either's tank.
In the end I will want a male GT though. No doubt.