Neuss 6/358 Rebuild kit & turbo wanted

Hi all,
This is for a friend. He needs to rebuild his smokey Inter C1800 with the infamous Neuss 6/358 engine. Where can he get a rebuild kit at a great price?

Also, to make it into a gutsy donk (hehehe), how about a turbo? Of cause, manifolds and other pipes and fittings would help too.

There is no immediate hurry as he parked it up and is working for someone else.

Anyone interested in buying it? He is considering selling it.

Thanks everyone, Tony