What exactly do you mean "sit level"? do you want to drop the shifter end down/or up a bit?
Remeber you want to keep your drive shaft as straight as possible, and I doubt the rear main seal would work very well if it was nearly completely submerged in oil.
Shades is already onto it though. Rx4 4 speeds and S1 rx7's have more of a "KE55" type shifter position while all other rx7 GB's are more of a back-of-the-extension-housing "KE70" position. My first suggestion would be to try and get your hands on a S1 5 speed and try that.
Can also always convert to a hydro handbrake!! :)
FYI, if there was ever a bible on mazda's....... then Spac wrote it. :) .......
http://ausrotary.com/viewtopic.php?f=16&t=2735