64-66 exhaust system on 68 coupe

So, i think i am going to go with the magnaflow. Only cause I just found some money, not literally, more like money was just freed up. I thought that i could turn in a 289 as a core for a 302, but you can't. Luckily my buddy is swaping his 302 for a 308 in his bronco, and he is just going to give me his 302 and I get to sell my 289 on top of that. Any takers?