I'll bite.... What is the reason you are against these swaps?
My 440 has aluminum heads, intake, water pump and housing and I would bet good money (by that I mean US dollars lol) that my car is as light as it was when it had the all cast iron 340 in it. yes yes of course if you went with lighter stuff on the 340 I get the advantage.
My car stays cool, has silly torque, handles great for a Mopar, and gets lots of a attention with the hood up.
To the OP, why are you swapping back? Not giving you a hard time, just curious.