Help me win this argument 400 in a 72.

The k-frame or motor mounts, radiator, exhaust, possible steering, driveshaft, and possibly rear end will have to be changed for the 400. IF you're going to that effort, i wouldn't waste it on a smoggy old 400.

The extra weight of a big-block makes for a car she may not like driving, especially if the power steering gets tossed. I want a 440 Valiant, but it would be a straight-line highway bruiser, really.