Big Block Conversion $$$

What makes the swap a whole lot easier, than in the past, is using these guys engine mounts and headers. Know matter what K member ya got they can supply the mounts for whatever engine and don't forget the torque rod. Myself and 3 other gentleman I know have used their products and no complaints so far. http://www.engine-swaps.com/
Other than these you're going to need the subframe connectors with the BB which may not be the case with the SB.
One other thing, if I was going to do the upgrade again I'd latch on to a good 400 block and stroke it to 451 which is what I have in mind for the 400 in my garage.

Terry