I actually L'ed O L at your math equation there Scott...
The 240/260/280 small block swap is SUPER common, simply because there's TONS of room in there. Hell, often more than in some of the vehicles Chevy put that motor in! (see: Corvette)
I think the trick would be to put it into something that wouldn't WAY F* up the balance of the car. The Nissan straight 6 is a BRICK, so it's not a huge issue in the 260/280 shell, but would a Trueno suffer from too much weight over the front tires? The SB isn't THAT heavy by comparison to some motors, but I'd guess much more than what the car was equipped with...
I don't really have any better ideas off the top of my head, but there's MY input on the current one!