An '83 760 with an automatic? You sure it's not a 1984? If it's really an '83, you've got a rare vehicle there -- don't change it!
As for your parts needs -- there was never an M47 sold with the turbodiesel motor -- you could make it work, but you'll have to build a frankenstein tranny out of parts from a 700 series diesel M46 and a gasser M47. Can be done but it will involve a pretty extensive shopping list in order to get all the little bits you'll need. You won't be able to find anyone who is able to sell you an actual complete 700 series diesel M47, those do exist, but they only came in European NA D24 740s.
There were not even many gas M47 700 series cars sold in the US so I suspect your biggest challenge will be finding the 700-series-specific M47 parts that you will need (e.g. driveshaft, mount/trans crossmember, shift linkage and cage if different from M46, etc). Some of it you may be able to fabricate or improvise from 740 M46 parts and 240 M47 parts but it may involve some trial and error. Note also that the pilot bearing I.D. on a diesel is different than a gas car, diesel transmissions come with a sleeve over the end of the input shaft that you'll need to get, otherwise it won't fit the diesel pilot. And a final note, the diesel bellhousings for 200 and 700 series cars are clocked differently so you'll need to make sure that your bellhousing comes off an M46 from a 740 or 760, not a 240.
Another thing you may struggle with is incompatibility of transmission mounting arragements -- all US 700-series diesels use a canted transmission mount that pairs with the canted engine mounts as a system, while later gas cars use more vertical, fluid-filled engine mounts and a vertical trans mount to match. I don't know how an M47 mounts in a 740, but if it has a vertical mount, you may need to find a way (perhaps using 240 parts?)... the first year for M47 was 1987 and IIRC the gassers had moved to the vertical mounts by then so this may indeed prove tricky. You'll also need all the parts for the clutch linkage (pedal, bracket, cable, electrical and vacuum switches for cruise if you want it to work right, console trim, shift boot, etc, etc, etc).
I also assume you already are aware of the M47's shortcomings and have plans for how to deal with them -- differences between series 1 and series 2 gearboxes, special oil requirements, 5th gear problems, etc. They're pretty easy to break, which is why they only were available in NA 8v and cars (even the B234F got an M46!), but if you can find a healthy one I imagine it could survive behind a stock D24T provided as drag racing isn't part of your plan. The thing to keep in mind is that later M47's are more robust than earlier ones, but late 700 series cars with manual shift are even more rare than earlier ones and '91 was the last year so 740s with M47-II transmissions really are hens' teeth. If you do get lucky and find a complete 700 series M47 package it will almost certainly be out of an earlier (late '80s) 740 which might mean you get the weaker tranny. In order to get the late M47, if that's what you want, into a 700 series diesel car, it might end up requiring purchasing a gas 240 transmission, a diesel 700 transmission, and all the 740 M47 parts a la carte...
Not trying to convince you not to do this, only pointing out that it will be quite a bit of parts-gathering and work! Putting in a diesel M46 would be much more straightforward, but comes with the tradeoffs of the M46. If you're intent on avoiding the M46 (which I can understand), then rather than going through a lot of effort to put in an M47, IMHO you might be better off adapting a T5 instead.
Out of curiosity, why do you want to convert to standard shift? Autobox failing, or just preference? Just as one other last thing to point out, in case you have not driven a D24T with a stick shift yet -- some people might argue that the ZF automatic behind the D24T is a much more refined setup overall. YMMV there.
