i did it on my 85. Took about half a day. Not that hard if you have all the tools. I did it right and used a rebuilt tranny from a doner car as well as a new clutch and pressure plate, throw out bearing, slave cylinder, master cylinder. From a doner car you will need a transmission, tranny cross member, clutch pedal assembly, brake pedal assemble, and the tubing that goes from the clutch master cylinder to the damper. I did not use the damper and did the 280 hose mod.
As far as cost I probably spent about $1200 but I did it with mostly new parts and that included rebuilding a tranny for $800. I am sure you can do it for less.
There are some step by step posts on some of the other web sites like maybe AZbums site and some others i have also seen. do some searching.