Early 1956 Valve Covers 9 Fin
 

Hello!
Over the weekend while cleaning out our garage I discovered some valve covers. I've done my homework and I think I've figured it out but I would really appreciate any help/knowledge from you guys.

Based off the pictures I've posted, can you tell me if the following is correct:
-They're early 56 covers but can be used on early 57's that aren't fuel inj.
-Staggered
-low script
-aluminum
-without casting flaw (that began mid-60's?)

Here's the question that's a dead giveaway I'm a woman :p How do I know whether or not they're aluminum or alloy? (I'm going with aluminum) and what can I use to clean them up?

Any help/knowledge/advice is welcomed & greatly appreciated!