I have a GM crate 350 and I added Blueprint heads, so no other parts from Blueprint. I was able to fit stock iron manifolds the first time around, but had to do some grinding around #7 plug, and use ceramic boots to protect the wires.
I then switched to Sanderson CC17 headers, which bolted in very easily. However, they came with angled collector adapters and the angles did not work well. Spent time cutting and fitting the adapters, and then MiG welded the pieces together. Passenger side is easy to fit, but on the drivers side you have to fit the flange and down pipe between the engine/trans flange and the shifter linkage. My shifter linkage lightly touches the collector in Park, but has space when it’s in gear.
One other issue with any shorty collector is that it’s back near the firewall, and hard to reach when working on a high truck. When tightening the collector flange bolts you have to hold the bolt and turn the nut (like usual), but need to be on top to hold one side and under the truck to reach the other side. Easy for two folks working, but hard for a single person.