driveshaft/pinion angle saga

[1stseries55]

need some opinions:

I am swapping a rear end from an 87 burb into my 65 GMC(leaf spring truck)

I moved the rear back approx 1" to compensate for flipping the rear above the leaf springs

with the move rearward the driveshaft still does not fit, it's close but the pionion angle would be off and the yoke is bottomed out in the tranny

I have to have the driveshaft shortened some...question is, how much?

I would think the yoke needs at least an inch to travel... then i need another 3/4 to 1 inch to set the pinion angle correctly.

so the yoke itself is 4"s long.... if i shorten the driveshaft 1.75--2"s will the 2" remaining in the tranny be enough?

what do you guys think? anyone done this on a leaf spring truck have any suggestions?

here is a pic that really is irrelevant but hey, we all like pics