Not the same. the 454 I'm putting into the '74 came out of a 78.
I ended up buying some from paragon.
I believe '74 manafold are different than a 66 (Just the left one is,but not a lot different) check my site for pictures http://mail.chartermi.net/~drhall/
I just looked. a 78 left one exits near the back straight down might work with a custom bent pipe??
the 78 right side exits out the very back with an angle down.probably too close to the cowel area of the car.
I could sent you some closer pics, Email if you want.
But if your in a hurry I won't be back until sunday .