If you want to put a 5 speed (or 6 speed) in your bird check out the following websites: http://www.keislerauto.com/ and http://www.5speedtransmissions.com/ They have just about everything you need, but it's not cheap. Almost 1/3rd of the price is converting from an auto to a stick, unless you locate used parts. You need the pedals, bellhousing, clutch, etc.
It looks like people doing the 5 speed swap are having best luck with the Tremec TKO tranny. It is a true overdrive tranny, with a 1:1 4th, and .64 (or .68) 5th gear. It would work well with numerically higher rear ends, like 3.42 and up. They handle big horsepower to.
The Richmond 5-speed is the one with a 1:1 fifth gear and it does seem strange. But it has a low 3.28 1st gear (TH400 has a 2.42 1st I think), so it works pretty well with a rear gear like a 2.78. One benefit of this setup would be lower driveshaft speed so your rear end would run cooler at extended high speeds.
There is also Doug Nash 5-speeds. I don't know anything about them.
Both of those websites will tell you the Tremec is the superior transmission.
I hope you decide to do it, cause I'm curious how it would turn out.
