Correct, I need about 3.5 to 4.0 degree wedges to get the rear facing down 2.75 to match up with the trans angle.
More likely to have vibration issues if you point the pinion down that far on a street driven deal. Those shim numbers give you a 5.1 to 5.6 down pinion, more than normal.
My deal and the way a lot of people do it. Under power you want the pinion, which rolls up under power, to be parallel with output shaft. In your case the trans is point down 2.75*. To get the pinion parallel, it needs to be pointing up 2.75* under power. So this is a guessing game of sorts. Measure with drivers weight in seat.
If you rolled the pinion down 2*, you'd be at .75* up. I usually run up to about 4* down on street cars. Race cars, especially leaf spring cars with no traction bars can go a lot more than 4* down.
JMO, for your car, if street driven, where it is would likely be OK at 1.10* up. A range of .75* up to 1.25* down would be my target if being nitpicky. If you don't have shims run it as is and see what you get. If it vibrates under acceleration, roll it down inside that range mentioned. See if the vibration goes away.
It's the relationship with your output shaft that tends to matter so the u joints phase properly. Rarely have we ever had to take the driveshaft angle into account. Exceptions, when the DS was pointing at an extreme angle.. like a lifted 4wd situation. And very rare occassion on cars.
Just my two cents.