280H with your L79 Intake and 600 Carb is 359.3 H.P with 386.8 Lbs of Torque your giving up 12Lbs of Torque over the XE268H and will have a worse Idle as well .

I was First thinking about the 270H but it gives up a Lot of Horse but the Torque is up 348 H.P with 399 Lbs of Torque . This was done with Comp Cams on Line Info .