Need help/advice concerning rear diff, M50 Swap

[crusheroz]

Newbie to the forums, sorry.
Question first as I tend to lose people. I need help finding a cheap and easy way to get 2.93 gears (or other suggestions) in my E30. Parts are limited, overseas shipping costs money for weight. (diffs)
Ok so, history:
I recently finished my E30 with E34 M50B25 engine/trans swap. I have a 3.64 rear diff from an E28, of course the 3.64 was installed while my M20 engine was in the car. It was good for the M20, got a few more mph on the autoban, but now I am looking to go with a 2.93 or something. I'm running somewhere around 4000 rpm at 120kph/70mph. At around 80kph, its around 2500rpm.
I'm looking to see if anyone has an easy fix since it was a lot of work putting this engine in and I'm really not looking forward to pulling it to rework the trans since everything bolts up and sits perfect with the original E30 mount and E36 drive shaft.
I've got a lot of time/money in this swap and man it was tiring and fun at the same time but I'm not thinking its gonna be that much more fun if I have to fit an E30 Getrag back in it.

Thanks in advance for anyone that can give some advice.