I probably said this before, but a 500 caddy with aluminium intake weighs less then a 350sbc, and has snot loads more torque. or so I've been told. Problem is, the Edelbrock aluminum intake will require you deleting your AC and possibly cutting a hole in your hood.
One day, I WILL verify this by weighing my 350sbc with Edelbrock intake compared to a 500Caddy with Edelbrock intake. Just need to buy the caddy intake and pull the engine out of my dad's Coupe De'ville when he's not looking. heheheehe...
For true weight comparison, it will be dressed, minus AC compressor which is a delete item anyways, and... hm... might have to find some caddy long tube headers for a G-body. Or take the exhaust manifolds off and compare that way. It is block to block comparison after all.
(Pops... build that 472 this summer so I can "borrow" your 500)