I hate recommending people but I would recommend Graham at Rawspeed in Plymouth he is a great VW engine guy, very good honest and top work. He can build up full motor and set up on a test rig and get delivered to you ready to put in and use, he has just rebuilt my 25hp motor for my 51.
Also I have a running complete long block which if you buy from me I can drop off to him.
Just a suggestion 😎