if you get a 13bre-cosmo, expect to rebuild it and bring it to someone to have them port it, and someone who knows how to extract the exhaust sleeves and to replace them with the ones out of your rotor housings. The ports are bigger then the rx7s, but not inside the engine, they choke them way down to give it more bottom end power, and they have restrictors in the exhaust ports which is why you have to change the sleeves. so, it might actually be more cost effective to rebuild yours, or find a used 3rd gen engine.