I have transplanted 455 olds engines into 2 old stove bolts a 63 chevy and 66 GMC using 1970 olds big car (delta 88/98 )motor mounts you need to enlarge the holes in the frame pads to bolt it right in then fabricate a cross member for what ever tranny you have.you can pick up a big oldsmobile boat cheap and most of them will have a 400 turbo tranny.these motors make upwards of 500 pnd/ft of torque and are capable of 18to19 mpg with the stock Qjet carb.73to77 cutlass headers will fit with minimum modification.stick a 750 Holley on top and you got a tire frying hot rod.
