Had a word with my dad, unfortunatly he cant remember it too well as it was a good few years ago.
We are pretty sure you have to use the transit flywheel, but not 100% certain.
What parts have you got in the kit?
Another thing to mention is that the transit inlet manifold needs altering, if there isnt one with the kit.
There should be some dowels, and some special bolts, and some new engine mounts to weld onto the chassis.
What gearbox do you have at the moment, the kit we had was for the 4speed box.
Hope this helps a bit, any other things feel free to ask, ill try to help. :D