Game Plan
After some great discussion with Dave (4+) regarding some of the conditions I am dealing with it makes more sense now or at least clarifies what's going on.
First, I prolly will not move the rear axel back as on the perches as suggested. One reason is there is so much travel on the rear axel the tire under stuff conditions will be only 1/2" to 3/4" from the fender lip with 33's. If I move it back I may have the tire shoved into the fender lips

No, I'm not going to trim the fenders

Next Dave made a point that even when you remove stock shocks on stock springs the rear DS cant be removed from flange because you cannot clear the pinion hub yet there is no bind and DS spins freely. The only condition that may be of concern would be both rear wheels off ground at the same time, not a realistic situation in a 60

So if I want to jump my 60 I guess I should redo the rear DS length

I do notice that even with lots of wheel travel at the rear there is very little movement at the rear DS. Now, the front with a SR is a whole different situation! The movement at the front axel is amazing with these springs and you really need to pay attention to clearance issues

Concerning the need for notching the cross member for the front DS clearance, this is an issue depending on the year of 60

I knew this but did not even think about it! Earlier years the 4-speeds don't have the 5th speed spacer in the tranny, mine is a 87'! Therefore the flange is set further back! In early years the DS flange clears the cross member when you use a DC front DS! So know anyone going to do this on a late model year truck (85 and later) a little more work to be done
In these pics you can see how the rear DS fits flange length just can't clear pinion hub. Second pics shows rear tire under stuff with 31x10.50's. Now, if I can eek by with 33x9.50's and not rip off my fender sheet metal, I may still try to move axel back on perches 1" to give me breathing room at rear DS.

Back to it today