I've talked to Stockton Wheel. They can do almost anything with wheels...for a price. If I can identify a stock GM wheel that's available from a wrecking yard, I can save maybe $500-$600 on a set of five. That's a worthy goal.
And yes, it has to be a GM wheel. They have the same contour in the center as the original wheels, so I can install clips and use the original hubcaps for the stock look.
Still looking for that website....
Joe