Looks GREAT Gary. This one should "Live" a lot longer than the 8 3/4 that was in there. One less thing to worry about and a very clean job.

As for perch mounting, it should be fine mounting them at the (2-degree modified) same angle as the Existing 8 3/4 rear, but I would have to agree with "LAR 414" as to the method of installing Perches at the Correct Pinion Angle being better done, IN the car.

That way being mounting the rear in the car with the Perches Loose, U-Bolts holding it together, Lowering the Full-Weight of the car to the Ground, adjusting Pinion-Angle, then Tack-Welding the Perches in place according to the Springs being used, etc.

If your Existing Rear (from the factory?) already has perches set to achieve, say 7-degrees, nose-down, or that 2-degrees you added gets you there, then you should be fine, but for most people it is better to actually SET the Perch/Pinion-Angle IN the car, tack-weld the perches, then remove the rear and Fully weld the perches on.

That way, the perches are more or less guaranteed to be the Correct or Desired New pinion-angle, as Mounted in the car. Also, side-to-side placement can be off due to production tolerances at the Factory, vehicle wear, Spring Location, etc, so Locating the Perches with the Rear Mounted IN the car can correct for existing, current conditions.

That is the Method I used when I mounted the Dana 60 rear in my car, last May.