Start simple and one axle at a time (front vs rear). While the symptoms appear similar the root cause may be different.
First, is the alignment shop equipment properly calibrated? Did the person doing the alignment know what they were doing? Yes, I have seen this. A quick check with a digital angle gauge should at least corroborate the difference in angles being reported by the shop. Seeing as how you just installed the D60, AND I'm assuming you did not jump the truck like the Duke brothers after the installation AND since the shop equipment is reporting a similar difference between front and rear I personally would not trust the report without some corroboration.
Second, work your way into the axle from the outside. Are the wheel bearings properly adjusted? Is there any play in the wheel/tire assembly? Did you properly torque all the fasteners when you put things back together? Is there any play in the outer "C"? You mentioned replacing the king pin bushings but what else did you do? Did you replace the bushing springs? Is the kingpin itself worn? Did you replace the lower bearing and race? Is there any play in the lower bearing? Is the lower bearing cap worn? Do you see any movement in the wheel/tire assembly (measure carefully) when you elevate the side (does the tire now sit vertical or with an outboard tilt)? In short, check all the adjustable and wear items to ensure they are properly installed, are not worn, and are not providing some inappropriate movement of the assembly.
After this you will need to start taking careful and detailed measurements to see if anything is off or bent like the spindle as mentioned above. I never advocate throwing parts at a problem (e.g. replace the spindle) until I understand the root cause of the issue. You can burn a lot of time and $ in doing so, although it can seem the easy approach as what I outlined above can be tedious.
The -34 Specs for camber are:
Camber M1009: + 8° M1009: ±0.5°All Except M1009: + 0° to + 1.5° All Except M1009: ± 0.5°
What was the source of your D60? Was it factory or modified? GM or other? This may also be a factor.
Lastly, GM designed a significantly greater amount of positive camber into the Blazer's much shorter wheelbase. Have you considered what any change in camber will do to the Blazer's handling?