nope, dont even NEED to change the logbook (well you do, but its the DVLA that want that done, not the MOT place)

and yes you need the speedo working... email stu_xr4x4@hotmail.com as he has some clocks you can use (with 2.0 DHOC revcounter and leccy speedo) and he should hopefully sell you them for a few pennies and postage