I am just on holday in Germany for 4 weeks, so no details here. Go to th E32 expert forum
http://www.bimmerboard.com/forums/e32/

To convert to vacuum operated system is basically possible from the H31, visit my website and look for the link to Max Fretter, he has done it but on a 735 (old 735 also had H31 system and later it was changed to vacuum operated). But there is little space in the 750 engine room.