[Isabo]

In my case a very wounded bank account!
My mechanic said it was a straightforward job. I already had a 915 gearbox fitted and the engine came from the mechanic's own SC as did the other bits to make it work, (he is fitting a 3.6). I don't know how typical a job mine was as my car is a bit of a mongrel with parts from lots of cars of different years.
This is what John Walker had to say when I first asked about the merits of the transplant:
the E needs to be a 70 or later for the flywheel/clutch assembly of the 3.0 to relate to the transmission. the 70/71 trans has a different bellhousing allowing for the pull type clutch of the 73-89 style. however, the 70/71 trans itself will be short lived with the power of the 3.0, so you should use a 73-86 trans for longevity. that also requires the later shifter, and drive flange changes depending on the year of the trans.
your car is not set up for the CIS system. it will need a fuel pump change, an accumulator, misc wiring changes, a tach, a CD unit (3.0 uses a 6 pin, you have a 3 pin), fuel line changes, but it can be done. best to find a wreck you can get all the parts from cheap.
the oil line from engine needs to be changed to the early, under the bellhousing style like you have now.
carbs would make the job a lot easier, but then there's their cost.
you would probably have 30 hours into the swap if you went to CIS, and the guy didn't waste any time. plus parts. $$$$$!