xr21780

Hi all can sum 1 help me out plz ive got a b reg 1.6 ghia non injection that i wnt to turbo ive got a complete xr3i escort that was turboed years ago by me and my mate im buyin the car engine swop i can change i know the box bolts up diff on a mk3 to a mk 4 if i use all the front end stuff of mk 4 will it bolt to the mk 3 so i can use the rst box and next when i change the loom how do i keep my cheak lights workin on my mk 3 or is it a no no ive been told dif storys that u can just change the bayloom in stead of the full lot can sum 1 explain plz or dose sum 1 know whos done it thanks guys