Info wanted on engine things...

Got a few questions for those veterans that have done these things.

Will a 273 crank (forged) fit in a 318 no problem?

Connecting rods on a 73 318, are they full floating type? Read that some are and some arent, anyway to tell besides tearing down the engine?

Magnum heads, are they aluminum or iron? Read that some arent and some are (Haha) and what kind of cars/trucks did the aluminum come on?

Also again, I read that magnum stock exhaust manifolds flow better on the driver side but not on the passenger side, compared to the 340HP. Could you put a magnum exhaust manifold on the driver side and a 340HP on the passenger side?

Just curious to these things. Also some place that sells the Magnum aluminum heads would be great!