I was wondering what, if any GM parts are interchageable with the caddy 500 engine, especially fuel injection setups. IF no such interchageable parts exist, who is a good aftermarket manufacturer of fuel injection setups for this engine (preferably multiport or tuned port setups). Ideally I'd like to shoot for 20 mpg without compromising power and torque...any ideas? this engine will be mounted to a TH-400 tranny and put in my 72 el camino