The Caddy will fit anywhere a BBC will, it's actually smaller in most dimensions, including weight.
HRM did that exact swap years ago. They took the 'Mino to the strip but never got a good time because everybody was having too much fun smoking the tires the full quarter! You just might have a slight traction problem.
I've had three Camino's, a '72 SS, an '82 SS, and still have a '74 Custom. Love 'em. Always wanted a 500 Caddy, but haven't found one yet.