Correct. Multiple holes in the stock perches. 1 1/8" is a number from memory. On the east coast for two weeks so no measurements or photos until July unfortunately. Moving the rear back to stock location means new driveshaft (or just cutting down which isn't too much $$). As a reference - the custom driveshaft, that fits with the current rearward axle, is 52 3/4". That's the measurement from the end of the trans case to the flat surface on the pinion yoke. No stock A-body 727 to 8.75 axle length measurement to compare in front of me.
Since I don't have my second set of tall rear wheels/tires yet I may just flip the perches to avoid the issue for now. My current tire combo will work with the axle in the stock location, though they look "forward". When I get the tall rears I can address it then.