I think PIM used to (or still sells) a kit which allows you to use the GP4 lens on stock buckets. Here's a "how-to" from MACMAN who's done the conversion.
http://pantera.infopop.cc/eve/forums/a/tpc/f/7650045562/m/5080003603/p/1
I think Larry is selling a set of Altissimo buckets on ebay right now. Pay yer money and you're done.
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