Alan, friend, do your homework and use the search function. "Suitable replacement transmissions" or something like that is a subject that has been discussed over and over again. IIRC the 260 is not what you want.
You want a Getrag 264 (4-speed) or 265 (five speed, 0.81 ratio overdrive fifth). There is a short list of BMWs that have had these transmissions. Most commonly, the E12s, but a few others as well.
Most will have mechanical speedometer drive (you want this) but you can get an electronic adapter to drive the electronic speedometer if you have no other choice, and the price of the trans is right. You'll also need (for the 265) the driveshaft from an auto trans coupe, clutch pedal, shifter linkage complete, clutch master and slave cylinders plus connecting hoses from the E12, and fluid reservoir from any old bimmer (I used one from a 2002 because I had one laying around).
Expect to replace some mounting bits. See this:
http://www.sehlin.com/cscoupe/tech/5speed/prep.html
Carl Nelson's article on the trans swap, while written for a Bavaria, was my point of reference.
