I believe there is a bit more to it than just the gear ratios and rod or cable change. I have a 16v trans which is cable change and has a hydro clutch. In order to put a 16v trans on an 8v, one would need cable shifter box + linkage, clutch + flywheel, clutch pedal hydro cylinder and the hydro actuator that is mounted on the trans, and i also believe the starter. Don't quote me on that, because I know that is what it would take for me to put the 16v trans on my 8v which i'm not going to do as it is more work that its really worth on a mk1.