Can this be paired with a 5-ton downflow A coil and keep the 14 SEER, if so, what coil do you recommend?

Yes, this unit can be paired with a 5 ton downflow A coil while keeping the 14 SEER. We have provided two coils that will work for you and that we recommend. The difference between these two coils it the width which will depend on the furnace that you currently have. If you have any further questions we recommend that you give us call. Thanks!