Hmmm- how did we let one of those escape across the pond?
I have a 300D turbo (sedan) that has a 722.315. I should think that would work in yours- but I'm not sure what all your options are in UK. I would think a (1)4 speed that (2) starts in 1st gear (3)with a Bowden cable (4) a modulator and a (5) 6-bolt sump SHOULD work. There may be some gassers that would work.
This Polish website, if you manupulate it, has some very good transmission data. I was able to glean some general data about my swap problem from there.
http://macmerc.netium.com.pl/index.html