cabrio 2000 16v engine conversion

i am currently trying to put a 2000 16 valve out of a mk 3 golf into my 1992 1800 carb golf clipper/cabrio i have purchased engine/gearbox/wiring loom speedo ecu and all acilaries.i am looking to here from someone who has done a conversion like this with any helpfull hints or tips plus any pitfalls A paticluler question i have do i use electrical dash or can i change the speedo drive in the gearbox for a manual one without afecting the ecu
any hepl apreshated:banghead: