60-66 Rear Axle Swap to 73-87 Rear Axle & Pinion Angle

[xwecer]

I'm swapping out the 12 bolt 3.73 axle on my 65 to a 3.07 12 bolt from a 77. I've ground off the old perches and have set the new axle on the trailing arms. I've done a bunch of research on setting the pinion angle and wanted to confirm some things before I weld them up since this is my first go round on doing this.

Here's some more detail. I plan on swapping out the two piece shaft for a one piece. I'm dropping the front with 2-1/2" drop spindles and 2" drop springs. I'm also dropping the rear with 3" drop springs. I currently have the motor/tranny mocked up and the angle on at the tranny is -3.5*. From my understanding the angle on the pinion yolk should then be +3.5* but not in line with the tranny, just parallel. Also, I've read on several threads that the pinion angle on a truck with leaf springs can change upwards of +2* under torque, but I only found one comment on a coil spring/trailing arm thread that stated the flex is only +.5*. Taking this into account should I set my pinion angle at +3* to account for the +.5*? Also, can someone confirm that the +/- range between the two angles can be 1* to 3*?

One caveat, this is all currently without load which I intend on adding, but wanted to make sure my understanding of setting the angle is right.

Thanks!