I owned a 65 2+2 with the 289hi-po. Recon is correct, the factory rated the engine at 271. You could however order it with some factory mods with they then rated the engine to 305. Mine came with these and if I remember correctly it was the carb and distributor that were different. Instead of a 600 vacuum operated secondary's 4 barrel it had 650 motorcraft manually operated carb and a dual point centrifugal distributor. This was a long time ago for me [ 68 ] but I think that's what it came with. I did a lot of mods to that car while I had it. One of those I wish I had back. Very fond memeories of that car.