Disco 200 tdi into 86 ex mod 2.5n/a

I have been looking and reading up for months. I have 90 ex mod with 2.5n/a and have disco 200 in garage and will start the conversion this month. Fly housing from n/a Steve Parker downpipe. Rad pipes pas pipes steering box from disco. Should I take out engine gearbox and tranny in one go or each one seperate etc which is easier ?

Have a look here http://www.landyzone.co.uk/lz/f7/2-5n-200tdi-conversion-168563.html Must get round to finishing it someday