u-joint angles

[85 K5]

I currently have 2.5 lift blocks in the rear. To reduce driveline vibration it was necessary to lower the transfer case. (spacers between frame and crossmember) I would like to put the transfer case back in it's original location and am wondering if rear lift springs would allow this, since the rear blocks are tapered.
Currently the rear ujoint angle is less because of the taper.
Did I once read that the u-joints need to be at the same angle? If so, rear springs and the transfer case in it's original location would put the u-joints at the same angle. Anyone know?