If you want to have a sky-is-the-limit IM built with a big engine and a 6-speed, Quaife America offers 6-speed transaxles with LS diff (actually the Quaife unit isn't really LS, but better). Lots of options available and bell housings to suit various Porsche (early 911 is VW) patterns. Don't know how much it would add to the cost; probably A LOT.
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