I have a good friend who has for sale an MPI engine & gearbox.
The engine needs a full re-build and is without the head. The gearbox is as original and should be OK, although a 'bit of a look' at it would be advisable.
He is looking for around £250.
It is in Cambridgeshire, in fact in my village.
PM me if interested and I'll give his phone numbers so that you can deal direct.