I tried this conversion this summer using a 911 rack, 930 tie rod ends and a 911 sterring column. I have a 66 912 so I took measurements from it to get the geometry right. Then I took out the beam and fabricated mounts for the rack just like the ones on my 912.
Everything bolted up okay...the tie rods ends are the same size as the ones on my car. I then cut out a hole in the center of the foot well as the 911 rack is centered unlike the VW unit which is in front of the driver.
The 911 column has 2 U joints to bring the column over to the driver's side (actually it can go either left or right hand drive). I used a 911 steering column, cut off the existing brackets and welded on a new one to bolt up to where the top of the VW column was attached.
When it was all done it did work but the steering wheel was wobbly. The VW column is supported at the top and bottom while the 911 column (as I installed) it was only supported at the top. I thought the bracket I made up would stablize it but it didn't...at least not to my liking. I ended up taking it all out and putting back in the VW unit...it was mid August and I hadn't driven my car yet in 2002!
It can be done and I don't think it would be all that difficult but I'm having second thoughts as to what you would gain. I replaced the ball joints on my car at the same time and that really tightened up the steering. I still have all the parts....911 rack, new 930 turbo tie rods, U jointed steering column and I may tackle it again next year or I may just sell the stuff on Ebay.