Ported t/a - aar heads HP? For an old 340 sprint car

Not building one just curious on what kind of HP people have gotten out of some ported U heads on a 340 or 360. A friend of mine has an old sprint car that ran a 340 from the mid 70s the 340 looks mostly stock other then it has a big cam alky hilborns and ported 6pack heads iam guessing it would be roughly 450HP at the crank. I will get some pictures as some of you guys would love to see this thing its a time capsule