Dont_Tri -
The only issue you may have, is that alot of "polished lips" wheels are machined finished, then clear-coated. You may find that this is the case for your wheels..
If in the direct, bright sunlight, if the reflection is somewhat "rainbowed" or has some prism-like effect, then most likely, it is cleared.. There's not alot of raw aluminum-polished wheels out there, anymore, as most people are too lazy to maintain the upkeep
My BBS wheels were cleared, as were my M-series BMW wheels I had.. Most of my other "polished" wheels have been cleared, as well.. I've actually owend only a couple sets of raw aluminum wheels, such as Centerline, and Bogarts. There's more out there, obviously, those are just two examples.
As for 1500g paper, check hardware stores, or bodyshop supply places. Ensure you get Wet-or-Dry paper. Keeping the paper wet also helps to keep the coarseness retained and aluminum from clogging up the paper..