Search eBay I'd say.

Do you have an air compressor?
I used a leak down tester to keep the valves up on the FTO motor, but on the 6G74 I used the rope method.
The rope method isn't as good since the valves tend to compress a bit before getting "stuck" which makes it a fair bit harder to install the retainer collets.

Also make sure this is not a car you need as it may take you a long time.
I think all up it took me well over 20 hours, but I am pretty slow (and careful) with these things