The best advice I can give is not to blindly follow my advice.
Today I took a flywheel out of the box and tried out what I had suggested about mounting it 45 degrees off from the flex plate. What I learned is that the eight bolts are not uniformly spaced and that the flex plate and flywheel only fit one way. The other news was that the way that it fit is with the gap 45 degrees off from how the flex plate mounts (I have an S6 2.7 TT flywheel and clutch). The other-other news is that I can't quite make sense out of what I said about the crank sensor and 66 degrees before TDC. Looking at where my flex plate lined up, I don't see how it's physically 66 degrees from TDC.
Here's one of the places I got it from:
To see the whole document, search for "V8-5VEngine.pdf".
Next...
There are a few good detailed swaps on the
audizine forum. 4Loops, Nollywood, and Bhusted really seem to know this stuff. Also "Silverd2" posts on a lot of the Audi forums and can be very helpful.
Here's a good thread you should read. Note the part about flywheel and spacer. It will be good to know if you need the spacer before you assemble and torque everything.
Detailed V8 Swap: B5 A4 4.2L
Exactly what I found with my flywheel is noted in post 9 of that thread. The
flex plate gap is about the 2:30 position at TDC. The
Flywheel gap is at about the 4:00 position. Why? The answer is in post 11: It corresponds with the position of the mounting for the G28 sensor on the Automatic and the Manual being shifted from the 8:30 position to the 10:00 position. I think I read all that a year ago and forgot it.
So the answer to the original question about the crankshaft sensor is: Buy the right flywheel and use the existing mount on the manual transmission. Easy. (But check your sensor to see if it needs a spacer for clearance)
I like to figure this stuff out as I go. If I get stumped and need professional help, I'd probably seek it directly from Qmulus on this forum.