You are gonna hate yourself for polishing those as it's a PITA to keep that way.
For a clear coating try this:
http://ppcco.com.au/topcoat_glistenpc.htm
An alternative which looks good is to give the carriers a good sand and remove casting ridges etc.
Give them a coat of POR15 silver which has a high aluminium solids content, sand the POR15 to achieve a perfect serface then follow with a coat of POR15 Stirling Silver. ( same site as above link)
Wear gloves when using POR15 as the only way to get it off your skin is to wait till the skin sheds.