My 91 S5 convt coolant seals are gone, it has an auto tranny, I bought a 87 S4 with a manual tranny. Can I install the s4 in the convt and use the s5 ancilliary equipment and motor controls? Can I remove the auto and install the manual tranny as well in the 91?

Or just fix the s5 motor and replace the auto tranny for the manual, any suggestions and ideas from RX7 owners are welcome, also what do you gain by porting a motor? I read about porting on this site but do not know what the benefit is, can you smog the car in Cali after its ported?

Thanks.